Domes were a characteristic element of the architecture ofAncient Rome and of its medieval continuation, theByzantine Empire. They had widespread influence on contemporary and later styles, fromRussian andOttoman architecture to theItalian Renaissance andmodern revivals. The domes were customarily hemispherical, although octagonal and segmented shapes are also known, and they developed in form, use, and structure over the centuries. Early examples rested directly on therotunda walls of round rooms and featured a centraloculus for ventilation and light.Pendentives became common in the Byzantine period, provided support for domes over square spaces.

Early wooden domes are known only from a literary source, but the use of woodenformwork, concrete, and unskilled labor enabled domes of monumental size in thelate Republic and earlyImperial period, such as the so-called "Temple of Mercury"bath hall atBaiae.Nero introduced the dome into Roman palace architecture in the 1st century and such rooms served as state banqueting halls, audience rooms, or throne rooms. ThePantheon's dome, the largest and most famous example, was built of concrete in the 2nd century and may have served as an audience hall forHadrian. Imperialmausolea, such as theMausoleum of Diocletian, were domed beginning in the 3rd century. Some smaller domes were built with a technique of using ceramic tubes in place of a wooden centering for concrete, or as a permanent structure embedded in the concrete, but light brick became the preferred building material over the course of the 4th and 5th centuries. Brick ribs allowed for a thinner structure and facilitated the use of windows in the supporting walls, replacing the need for an oculus as a light source.

Christianbaptisteries andshrines were domed in the 4th century, such as theLateran Baptistery and the likely wooden dome over theChurch of the Holy Sepulchre. Constantine'soctagonal church in Antioch may have been a precedent for similar buildings for centuries afterward. The first domedbasilica may have been built in the 5th century, with a church in southern Turkey being the earliest proposed example, but the 6th century architecture ofJustinian made domed church architecture standard throughout the Roman east. HisHagia Sophia andChurch of the Holy Apostles inspired copies in later centuries.

Cruciform churches with domes at their crossings, such as the churches ofHagia Sophia in Thessaloniki andSt. Nicholas at Myra, were typical of 7th and 8th century architecture and bracing a dome withbarrel vaults on four sides became the standard structural system. Domes over windoweddrums of cylindrical or polygonal shape were standard after the 9th century. In the empire's later period, smaller churches were built with smallerdiameter domes, normally less than 6 meters (20 ft) after the 10th century. Exceptions include the 11th century domed-octagons of Hosios Loukas andNea Moni, and the 12th centuryChora Church, among others. Thecross-in-square plan, with a single dome at the crossing or five domes in aquincunx pattern, as at theChurch of St. Panteleimon, was the most popular type from the 10th century until thefall of Constantinople in 1453.

Rounded arches, vaults, and domes distinguishRoman architecture fromthat of Ancient Greece and were facilitated by the use ofconcrete and brick.^[1] By varying the weight of the aggregate material in the concrete, the weight of the concrete could be altered, allowing lighter layers to be laid at the top of concrete domes. But concrete domes also required expensive woodenformwork, also called shuttering, to be built and kept in place during the curing process, which would usually have to be destroyed to be removed. Formwork for brick domes need not be kept in place as long and could be more easily reused.^[2] The mortar and aggregate of Roman concrete was built up in horizontal layers laid by hand against wooden form-work with the thickness of the layers determined by the length of the workday, rather than being poured into a mold as concrete is today. Roman concrete domes were thus built similarly to the earlier corbel domes of the Mediterranean region, although they have different structural characteristics.^[3][4] The aggregate used by the Romans was often rubble, but lightweight aggregate in the upper levels served to reduce stresses.^[5] Empty "vases and jugs" could be hidden inside to reduce weight.^[6] The dry concrete mixtures used by the Romans were compacted with rams to eliminate voids, and added animal blood acted as a water reducer.^[7] Because Roman concrete was weak in tension, it did not provide any structural advantage over the use of brick or stone. But, because it could be constructed with unskilled slave labor, it provided a constructional advantage and facilitated the building of large-scale domes.^[8]

Roman domes were used inbaths, villas, palaces, and tombs.Oculi were common features.^[9] They were customarily hemispherical in shape and partially or totally concealed on the exterior. In order to buttress the horizontal thrusts of a large hemispherical masonry dome, the supporting walls were built up beyond the base to at least the haunches of the dome and the dome was then also sometimes covered with a conical or polygonal roof.^[10] A variety of other shapes, including shallowsaucer domes,segmental domes, andribbed domes were also sometimes used.^[11] Stone or brick ribs were usually flush with the inside surface of Roman domes where they would not have been visible.^[12] The audience halls of many imperial palaces were domed.^[13] Domes were "closely associated with senatorial, imperial, and state-sponsored patrons" and proliferated in the capital cities and other cities with imperial affiliations.^[14] Domes were also very common over polygonal garden pavilions.^[15] Depictions on late Roman coins suggest that wooden bulbous domes sheathed in metal were used on late Roman towers in the eastern portion of the empire.^[16] Construction and development of domes declined in the west with the decline and fall of the western portion of the empire.^[17]

InByzantine architecture, a supporting structure of four arches withpendentives between them allowed the spaces below domes to be opened up. Pendentives allowed for weight loads to be concentrated at just four points on a more practical squareplan, rather than a circle.^[18] Until the 9th century, domes were low with thick buttressing and did not project much into the exterior of their buildings. Drums were cylindrical when used and likewise low and thick. After the 9th century, domes were built higher and used polygonal drums decorated with engaged columns and arcades. Exterior dome decoration was more elaborate by the 12th century and included engaged columns along with niches, blind arcades, and string courses. Multiple domes on a single building were normal.^[19] A "so-called 'Athenian dome'" type had an octagonal drum with a corrugated cornice of semi-circular eaves and a thin marble column at each corner. Typically there was a single window on each side of the octagon.^[20]

Domes were important elements ofbaptisteries, churches, and tombs.^[21] They were normally hemispherical and had, with occasional exceptions, windowed drums. Roofing for domes ranged from simpleceramic tile to more expensive, more durable, and more form-fitting lead sheeting.^[22] The domes and drums typically incorporated wooden tension rings at several levels to resist deformation in the mortar and allow for faster construction. Metal clamps between stone cornice blocks, metal tie rods, and metal chains were also used to stabilize domed buildings.^[23] Timber belts at the bases of domes helped to stabilize the walls below them during earthquakes, but the domes themselves remained vulnerable to collapse.^[24] The surviving ribbed or pumpkin dome examples inConstantinople are structurally equivalent and those techniques were used interchangeably, with the number of divisions corresponding to the number of windows. Aided by the small scale of churches after the 6th century, such ribbed domes could be built with formwork only for the ribs. Pumpkin domes could have been built in self-supporting rings and small domical vaults were effectively corbelled, dispensing with formwork altogether.^[25]

The circular oculus of thePantheon, at the center of the domed ceiling

The dome ofSanta Costanza is concealed externally by the buttressing of its cylindrical drum

A dome of the formerPantokrator Monastery, showing an exposed external profile and lead roofing

A dome atChora Church, with ribs from between the drum windows converging on a circular fresco image

Roman baths played a leading role in the development of domed construction in general, and monumental domes in particular. Modest domes in baths dating from the 2nd and 1st centuries BC are seen inPompeii, in thecold rooms of theTerme Stabiane and theTerme del Foro [it].^[26][27] These domes are very conical in shape, similar to those on anAssyrian bas-relief found inNineveh.^[28][29] At a Roman eratepidarium inCabrera de Mar, Spain, a dome has been identified from the middle of the 2nd century BC that used a refined version of the parallel arch construction found in an earlier Hellenistic bath dome in Sicily.^[30] According toVitruvius, the temperature and humidity of domed warm rooms could be regulated by raising or lowering bronze discs located under an oculus.^[31] Domes were particularly well suited to thehot rooms of baths circular in plan to facilitate even heating from the walls. However, the extensive use of domes did not occur before the 1st century AD.^[32]

Varro's book on agriculture describes an aviary (Varro's Aviary) with a wooden dome decorated with the eight winds that is compared by analogy to the eight winds depicted on theTower of the Winds, which was built inAthens at about the same time. This aviary with its wooden dome may represent a fully developed type. Wooden domes in general would have allowed for very wide spans. Their earlier use may have inspired the development and introduction of large stone domes of previously unprecedented size.^[26] Complex wooden forms were necessary for dome centering and support during construction, and they seem to have eventually become more efficient and standardized over time.^[33] The "so-calledtomb of Ummidia [it]" is a domed Greek cross structure dated to either the 1st century BC or the 1st century AD. The hemispherical dome was made from large stone ashlar blocks pierced by four holes with shafts extending diagonally up to the outside surface.^[34]

Domes reached monumental size in the RomanImperial period.^[26] Although imprints of the formwork itself have not survived, deformations from the ideal of up to 22 centimeters (8.7 in) at the so-called "Temple of Mercury" in Baiae suggest a centering of eight radiating frames, with horizontal connectors supporting radial formwork for the shallow dome.^[35] The building, actually a concretefrigidarium pool for abath, dates to either the late Roman Republic,^[36] or the reign of the firstemperorAugustus (27 BC – 14 AD), making it the first large Roman dome. There are five openings in the dome: a circular oculus and four square skylights.^[26] The dome has a span of 21.5 meters (71 ft) and is the largest known dome built before that of the Pantheon.^[37] It is also the earliest preserved concrete dome.^[33]

While there are earlier examples in theRepublican period and early Imperial period, the growth of domed construction increased underEmperor Nero andthe Flavians in the 1st century AD, and during the 2nd century. Centrally planned halls become increasingly important parts of palace and palace villa layouts beginning in the 1st century, serving as state banqueting halls, audience rooms, or throne rooms.^[38] Formwork was arranged either horizontally or radially, but there is not enough surviving evidence from the 1st and 2nd centuries to say what was typical.^[33]

The opulent palace architecture of the Emperor Nero (54 – 68 AD) marks an important development.^[39] There is evidence of a dome in hisDomus Transitoria at the intersection of two corridors, resting on four largepiers, which may have had an oculus at the center. In Nero'sDomus Aurea, or "Golden House", planned by Severus and Celer, the walls of a large octagonal room transition to an octagonal domical vault, which then transitions to a dome with an oculus.^[40][41] This is the earliest known example of a dome in the city of Rome itself.^[35]

The Domus Aurea was built after 64 AD and the dome was over 13 meters (43 ft) in diameter.^[42] The exterior diameter of the octagonal room was 14.65 meters (48.1 ft) meters and the diameter of the oculus was 5.925.92 meters (19.4 ft) meters. The height of the dome (4.79 meters (15.7 ft)) was about equal to the height of the supporting walls (4.91 meters (16.1 ft)). The dome transitions from an octagonal plan to a circular plan at about 2 meters (6 ft 7 in) above its springing.^[43] This octagonal and semicircular dome is made of concrete and the oculus is made of brick. The radial walls of the surrounding rooms buttress the dome, allowing the octagonal walls directly beneath it to contain large openings underflat arches and for the room itself to be unusually well lit.^[44] Because there is no indication that mosaic or other facing material had ever been applied to the surface of the dome, it may have been hidden behind a tent-like fabric canopy like the pavilion tents of Hellenistic (and earlier Persian) rulers. The oculus is unusually large, more than two-fifths the span of the room, and it may have served to support a lightweight lantern structure ortholos, which would have covered the opening. Circular channels on the upper surface of the oculus also support the idea that this lantern, perhaps itself domed, was the rotating dome referred to in written accounts.^[45] A rainwater drainage manhole in the floor at the center of the room, beneath the open oculus, has since been covered.^[46]

According toSuetonius, the Domus Aurea had a dome that perpetually rotated on its base in imitation of the sky.^[47] It was reported in 2009 that newly discovered foundations of a round room may be those of a rotating domed dining hall.^[48] Also reported in contemporary sources is a ceiling over a dining hall in the palace fitted with pipes so that perfume could rain from the ceiling, although it is not known whether this was a feature of the same dome.^[49] The expensive and lavish decoration of the palace caused such scandal that it was abandoned soon after Nero's death and public buildings such as theBaths of Titus and theColosseum were built at the site.^[50]

The only intact dome from the reign ofEmperor Domitian is a 16.1-meter (53 ft) wide example in what may have been a nymphaeum at his villa atAlbano. It is now the church ofSanta Maria della Rotunda [it].^[42] Domitian's 92 ADDomus Augustana established the apsidalsemi-dome as an imperial motif.^[13] Square chambers in his palace on the Palatine Hill used pendentives to support domes.^[51] His palace contained three domes resting over walls with alternating apses and rectangular openings.^[52] An octagonal domed hall existed in the domestic wing.^[53] Unlike Nero's similar octagonal dome, its segments extended all the way to the oculus.^[13] The dining hall of this private palace, called theCoenatio Jovis, or Dining Hall of Jupiter, contained a rotating ceiling like the one Nero had built, but with stars set into the simulated sky.^[54]

During the reign ofEmperor Trajan, domes and semi-domes overexedras were standard elements of Roman architecture, possibly due to the efforts of Trajan's architect,Apollodorus of Damascus, who was famed for his engineering ability.^[55][56] Two rotundas 20 meters (66 ft) in diameter were finished in 109 AD as part of theBaths of Trajan, built over the Domus Aurea, and exedras 13 and 18 meters (43 and 59 ft) wide were built as part of themarkets north-east of his forum. The architecture of Trajan's successor, Hadrian, continued this style.^[55] Three 100-foot (30 m) wide exedras at Trajan's Baths have patterns of coffering that, as in the later Pantheon, align with lower niches only on the axes and diagonals and, also as in the Pantheon, that alignment is sometimes with the ribs between the coffers, rather than with the coffers themselves.^[56] Apollodorus may have designed the two 150-foot (46 m) wide wooden half-domes on the exedras of Trajan'sBasilica Ulpia, but no documents concerning these structures have survived.^[57]

ThePantheon in Rome, completed byEmperor Hadrian as part of theBaths of Agrippa, has the most famous, best preserved, and largest Roman dome.^[58] Its diameter was more than twice as wide as any known earlier dome.^[59] The dome of the Pantheon is unreinforced concrete spanning 43.4 meters (142 ft) and resting on a circular wall, orrotunda, 6 meters (20 ft) thick. This rotunda, made of brick-faced concrete, contains a large number ofrelieving arches and voids. Seven interior niches and the entrance way divide the wall structurally into eight virtually independent piers. These openings and additional voids account for a quarter of the rotunda wall's volume. The only opening in the dome is the brick-lined oculus at the top, 9 meters (30 ft) in diameter, that provides light and ventilation for the interior.^[60] The shallowcoffering in the dome accounts for a less than five percent reduction in the dome's mass, and is mostly decorative. The aggregate material hand-placed in the concrete is heaviest at the base of the dome and changes to lighter materials as the height increases, dramatically reducing the stresses in the finished structure.^[60]

Although considered an example of Hadrianic architecture, there isbrickstamp evidence that the rebuilding of the Pantheon in its present form was begun under Trajan.^[50] Speculation that the architect of the Pantheon was Apollodorus has not been proven, although there are stylistic commonalities between his large coffered half-domes at Trajan's Baths and the dome of the Pantheon.^[56] Other indicators that the designer was either Apollodorus or someone in his circle who was "closer in artistic sensibility to Trajan’s era than Hadrian’s" are the monumental size and the incorporation of tiny passages in the structure. The building's dimensions seem to referenceArchimedes' treatiseOn the Sphere and Cylinder, the dome may use rows of 28 coffers because 28 was considered by thePythagoreans to be aperfect number, and the design balances its complexity with underlying geometrical simplicity.^[61] Hadrian was an amateur architect and it was apparently domes of Hadrian's like the later examples at his villa in Tivoli that Apollodorus derisively calledgourds prior to Hadrian becoming emperor. According toCassius Dio, the memory of this insult contributed to Hadrian as emperor having Apollodorus exiled and killed.^[62] The inscription on the Pantheon falsely attributed this third building at the site to the builder of the first,Marcus Agrippa.^[63]

The function of the Pantheon remains an open question. Strangely for a temple, its inscription does not mention any god or group of gods. Its name,Pantheon, comes from the Greek for "all gods" but is unofficial, and it was not included in the list of temples restored by Hadrian in theHistoria Augusta. Circular temples were small and rare, and Roman temples traditionally allowed for only one divinity per room. The Pantheon more resembles structures found in imperial palaces and baths. Hadrian is believed to have held court in the rotunda using the main apse opposite the entrance as atribune, which may explain its very large size.^[63] Later Roman buildings similar to the Pantheon include atemple to Asklepios Soter [de] (c. 145) in the old Hellenistic city ofPergamon and the so-called"Round Temple" [it] atOstia (c. 230–240), which may have been related to theImperial cult. The Pergamon dome was about 80Roman feet wide, versus about 150 for the Pantheon, and made of brick over a cut stone rotunda. The Ostia dome was 60 Roman feet wide and made of brick-faced concrete.^[64][65] No later dome built in the Imperial era came close to the span of the Pantheon.^[66] It remained the largest dome in the world for more than a millennium and is still the world's largestunreinforced concrete dome.^[67]

Many commentators have cited the Pantheon as an example of therevolutionary possibilities formonolithic architecture provided by the use of Romanpozzolana concrete. However, vertical cracks seem to have developed very early, such that in practice the dome acts as an array of arches with a common keystone, rather than as a single unit. The exterior step-rings used to compress the "haunches" of the dome, which would not be necessary if the dome acted as amonolithic structure, may be an acknowledgement of this by the builders themselves. Such buttressing was common in Roman arch construction.^[60] The cracks in the dome can be seen from the upper internal chambers of the rotunda, but have been covered by re-rendering on the inside surface of the dome and by patching on the outside of the building.^[68] The Pantheon's roof was originally covered with gilt bronze tiles, but these were removed in 663 byEmperor Constans II and replaced with lead roofing.^[29][69]

Use of concrete facilitated the complex geometry of the octagonal domed hall at the 2nd century Small Thermal Baths ofHadrian's Villa inTivoli. The vaulting has collapsed, but a virtual reconstruction suggests that the walls of the octagonal hall, which alternate flat and convex, merged into a spherical cap.^[70] Segmented domes made of radially concave wedges, or of alternating concave and flat wedges, appear under Hadrian in the 2nd century and most preserved examples of the style date from this period. Hadrian's villa has examples at the Piazza D'Oro and in the semidome of the Serapeum. Recorded details of the decoration of the segmented dome at the Piazza D'Oro suggests it was made to evoke a billowing tent, perhaps in imitation of the canopies used byHellenistic kings. Other examples exist at the Hadrianic baths ofOtricoli and the so-called "Temple of Venus" at Baiae. This style of dome required complex centering and radially oriented formwork to create its tight curves, and the earliest surviving direct evidence of radial formwork is found at the caldarium of the Large Baths at Hadrian's villa.^[71]

In the middle of the 2nd century, some of the largest domes were built near present-dayNaples, as part of large bath complexes taking advantage of the volcanic hot springs in the area. At the bath complex at Baiae, there are remains of a collapsed dome spanning 26.3 meters (86 ft), called the "Temple of Venus", and a larger half-collapsed dome spanning 29.5 meters (97 ft) called the "Temple of Diana". The dome of the "Temple of Diana", which may have been anymphaeum as part of the bath complex, can be seen to have had anogival section made of horizontal layers of mortared brick and capped with light tufa. It dates to the second half of the 2nd century and is the third largest dome known from the Roman world. The second largest is the collapsed "Temple of Apollo" built nearby along the shore ofLake Avernus. The span cannot be precisely measured due to its ruined state, but it was more than 36 meters (118 ft) in diameter.^[72]

Octagonal rooms of theBaths of Antoninus inCarthage were covered with cloister vaults and have been dated to 145–160.^[73]

In the second half of the 2nd century in North Africa, a distinctive type of nozzle tube shape was developed in the tradition of the terracotta tube dome at the Hellenistic era baths of Morgantina, an idea that had been preserved in the use of interlocking terracotta pots for kiln roofs. This tube could be mass-produced on potter's wheels and interlocked to form a permanent centering for concrete domes, avoiding the use of wooden centering altogether. This spread mainly in the western Mediterranean.^[74]

Although rarely used, the pendentive dome was known in 2nd century Roman architecture and possibly earlier, in funerary monuments such as theSedia dei Diavolo [it] and theTorracio della Secchina [it] on theVia Nomentana. Pendentive domes would be used much more widely in the Byzantine period.^[75][76] A "Roman tomb in Palestine at Kusr-en-Nêuijîs" had a pendentive dome over the square intersection of cruciform barrel vaults and has been dated to the 2nd century.^[77] A small dome on spherical pendentives atBeurey-Beauguay on theCôte-d'Or department of France has been dated to the 2nd or 3rd century.^[76] A stone voussoir dome over the caldarium of the West Bath ofJerash has been dated to the second century.^[78] One of apparently three domes in the west bath complex, the northern 6.9 meter diameter sail vault has survived intact.^[79]

The large rotunda of the Baths of Agrippa, the oldest public baths in Rome, has been dated to theSeveran period at the beginning of the 3rd century, but it is not known whether this is an addition or simply a reconstruction of an earlier domed rotunda.^[80]

In the 3rd century, imperial mausolea began to be built as domed rotundas rather thantumulus structures or other types, following similar monuments by private citizens. Pagan andChristian domed mausolea from this time can be differentiated in that the structures of the buildings also reflect their religious functions. The pagan buildings are typically two story, dimly lit, free-standing structures with a lower crypt area for the remains and an upper area for devotional sacrifice. Christian domed mausolea contain a single well-lit space and are usually attached to achurch.^[81] The use of the circular or octagonal domed rotunda for imperial mausolea began withEmperor Gallienus in the 260s and the type would be used throughout the late-antique period.^[82] Thefirst St. Peter's Basilica would later be built near a preexisting early 3rd century domed rotunda that may have been a mausoleum. In the 5th century the rotunda would be dedicated toSt. Andrew and joined to theMausoleum of Honorius.^[83][84] An example from the 3rd century is the mausoleum atVilla Gordiani.^[85] The Villa Gordiani also contains remains of an oval gored dome.^[86]

Masonry domes were less common in the Roman provinces, although the 3rd century "Temple of Venus" atBaalbek was built with a stone dome 10 meters (33 ft) in diameter.^[15] A stone corbelled dome 5.806 meters (19.05 ft) wide, later known as "Arthur's O'on", was located inScotland three kilometers north of theFalkirk fort on theAntonine Wall and may have been a Roman victory monument from the reign ofCarausius. It was destroyed in 1743.^[87]

The technique of building lightweight domes with interlocking hollow ceramic tubes further developed in North Africa and Italy in the late 3rd and early 4th centuries.^[88] By the 4th century, the thin and lightweight tubed vaulting had become a vaulting technique in its own right, rather than simply serving as a permanent centering for concrete. It was used in early Christian buildings in Italy.^[89] Arranging these terracotta tubes in a continuous spiral created a dome that was not strong enough for very large spans, but required only minimal centering and formwork.^[90] The later dome of theBaptistry of Neon inRavenna is an example.^[88]

In the 4th century, Roman domes proliferated due to changes in the way domes were constructed, including advances incentering techniques and the use of brickribbing. The so-called "Temple of Minerva Medica", for example, used brick ribs along with step-rings and lightweight pumice aggregate concrete to form adecagonal dome.^[91] The material of choice in construction gradually transitioned during the 4th and 5th centuries from stone or concrete to lighter brick in thin shells.^[92] The use of ribs stiffened the structure, allowing domes to be thinner with less massive supporting walls. Windows were often used in these walls and replaced the oculus as a source of light, although buttressing was sometimes necessary to compensate for large openings. TheMausoleum of Santa Costanza has windows beneath the dome and nothing but paired columns beneath that, using a surroundingbarrel vault to buttress the structure.^[93]

TheMausoleum of Diocletian uses small arched squinches of brick built up from a circular base in an overlapping scales pattern, called a "stepped squinches dome". The scales pattern was a popular Hellenistic motif adopted by theParthians andSasanians, and such domes are likely related to Persian "squinch vaults".^[94] The inner diameter of the building is 13.35 meters.^[95] The only light source in the building is a single window just below the dome that was added in the 17th century. Deformations at the top of the dome indicate possible modification, supporting speculation that there may have originally been an oculus. Radial iron anchors from the Roman era were discovered in the dome during a restoration. A lower crypt chamber is also domed. The mausoleum was built in 305 within the imperial palace.^[96]

In addition to the mausoleum, thePalace of Diocletian also contains a rotunda near the center of the complex that may have served as a throne room. It has side niches similar to those of an octagonal mausoleum but was located at the end of an apparently barrel-vaulted hall like the arrangement found in later Sasanian palaces.^[97]

TheRotunda of Galerius, with its 24-meter (79 ft) dome, was built close to the imperial palace around 300 AD as either a mausoleum or a throne room. It was converted into a church in the 5th century.^[98] The dome appears to have originally been built with sixteenlunette windows at its base, eight of which were filled in prior to the placement of the surviving dome mosaics. The remaining lunette windows have since been reduced to small square windows. The east end of the building was reconstructed in the 11th century and an additional lunette window was added at that time on that side, along with reconstruction of the two adjacent lunettes.^[99] Also in Thessaloniki, at theTetrarchic palace, an octagonal building has been excavated with a 24.95 meter span that may have been used as a throne room. It is known not to have been used as a church and was unsuitable as a mausoleum, and was used for some period between about 311 and when it was destroyed before about 450.^[100] Remains of two mausolea atGamzigrad are believed to have been domed and used as the resting places ofGalerius and his mother Romula. The mausoleum of Galerius seems to have been similar to that of Diocletian and may have used it as a model.^[101]

A Tetrarchic imperial mausoleum has been excavated atŠarkamen, with a brick domed lower chamber preserved, and its similarity to the Gamzigrad mausolea has led to speculation that the same architect designed it. It may have been built for the mother ofMaximinus Daza.^[102]

TheMausoleum of Helena (c. 315-327) was the first imperial mausoleum for a Christian, Constantine's mother, and was attached to theBasilica of Saints Marcellinus and Petrus. The inside of the rotunda was a single well-lit space 20.18 meters in diameter with no lower chamber. The drum had eight windows set in exterior niches and there is no evidence of an oculus in the ceiling. The dome was constructed with hollow jars calledpignatte [it] and it was decorated with mosaics.^[103]

The octagonal "Domus Aurea", or "Golden Octagon", built byEmperor Constantine in 327 at the imperial palace ofAntioch likewise had a domical roof, presumably of wood and covered with gilded lead.^[104][105] Also called "the Octagon" or "Great Church", the central octagonal domed space was apparently surrounded by a two-story ambulatory with columns in a similar billowing pattern to the later church of San Lorenzo in Milan.^[106] It was dedicated two years after theCouncil of Nicea to "Harmony, the divine power that unites Universe, Church, and Empire". It may have been both the cathedral of Antioch as well as the court church of Constantine, and the precedent for the later octagonal plan churches near palaces ofSaints Sergius and Bacchus andHagia Sophia by Justinian andAachen Cathedral by Charlemagne.^[107] The dome was rebuilt by 537–8 withcypress wood from Daphne after being destroyed in a fire. Most domes on churches in the Syrian region were built of wood, like that of the laterDome of the Rock in Jerusalem, and the dome of the Domus Aurea survived a series of earthquakes in the 6th century that destroyed the rest of the building. There is no record of the church being rebuilt after the earthquake of 588, perhaps due to the general abandonment of many public buildings in what was no longer a capital of the Empire.^[108]

Constantine built theChurch of the Nativity in Bethlehem around 333 as a large basilica with an octagonal structure at the eastern end, over the cave said to be the birthplace of Jesus. The domed octagon had an external diameter of 18 meters.^[109][110] It was later destroyed and when rebuilt by Justinian the octagon was replaced with a tri-apsidal structure.^[109]

Centralized buildings of circular or octagonal plan also became used for baptistries andreliquaries due to the suitability of those shapes for assembly around a single object.^[111] Baptisteries began to be built in the manner of domed mausolea during the 4th century in Italy. The octagonalLateran Baptistery or the baptistery of the Holy Sepulchre may have been the first, and the style spread during the 5th century.^[112] The dome of the Lateran Baptistery was replaced in the seventeenth century.^[113] In the second half of the fourth century, domed octagonal baptisteries similar to the form of contemporary imperial mausolea developed in the region of North Italy near Milan.^[114] Examples of domed baptisteries include theBaptistery of San Giovanni in Fonte in Milan [it] (late 4th century), a baptistery inAquileia (late 4th century), and adomed baptistery in Naples (4th to 6th centuries).^[115]

Part of a baths complex begun in the early 4th century, the brickChurch of St. George inSofia was acaldarium that was converted in the middle of the fifth century. It is a rotunda with four apse niches in the corners.^[116] The best preserved example of Roman architecture in the city, it has been used as a baptistery, church, mosque, and mausoleum over the centuries. The dome rises to about 14 m from the floor with a diameter of about 9.5 m.^[117] Its original function as ahypocaust hall is disputed and, based on its form, the building may originally have been a Christian martyrium. It was half-destroyed by theHuns in 447 and was rebuilt in the 11th century.^[118]

In the middle of the 4th century in Rome, domes were built as part of theBaths of Constantine and theBaths of Helena [it]. Domes over the calderia, or hot rooms, of the olderBaths of Agrippa and theBaths of Caracalla were also rebuilt at this time.^[119]

Between the second half of the 4th century and the middle of the 5th century, domed mausolea for wealthy families were built attached to a new type of martyrial basilica before burials within the basilica itself, closer to the martyr's remains, made such attached buildings obsolete.^[120] A pagan rotunda from this period located on theVia Sacra was later incorporated into theBasilica of Saints Cosmas and Damian as avestibule around 526.^[83] Thechapel of S. Satiro in Milan [it] was built with a dome using the pottery technique of Ravenna, and was later connected to the Basilica of Sant'Ambrogio.^[121] TheMausoleum of Santa Costanza was built attached to the south wall of the cemetery basilica of St. Agnes and consists of an 11.5 meter wide dome supported by twelve pairs of columns and a surrounding vaulted ambulatory. The dome's mosaic has not survived but its design was recorded in drawings showing that it combined pagan and Christian elements, indicating a date of completion in the middle of the fourth century.^[122]

Christian mausolea andshrines developed into the "centralized church" type, often with a dome over a raised central space.^[111] TheChurch of the Holy Apostles, orApostoleion, probably planned by Constantine but built by his successorConstantius in the new capital city of Constantinople, combined the congregational basilica with the centralized shrine. It may have had a similar plan to that of theChurch of Saint Simeon Stylites, with four naves projected from a central rotunda containing Constantine's tomb and spaces for the tombs of thetwelve Apostles.^[123] Above the center may have been aclerestory with a wooden dome roofed with bronze sheeting and gold accents.^[124] There are different interpretations of the description of Constantine's mausoleum and its relation to the cruciform Church of the Holy Apostles, but it may have been built as a domed rotunda to which Constantius later added a cruciform basilica.^[82]

The oblong decagon of today'sSt. Gereon's Basilica inCologne, Germany, was built upon an extraordinary and richly decorated 4th century Roman building with an apse, semi-domed niches, and dome. A church built in the city's northern cemetery, its original dedication is unknown.^[125] It may have been built byJulianus, the governor ofGaul from 355 to 360 who would later become emperor, as a mausoleum for his family.^[126] The oval space may have been patterned after imperial audience halls or buildings such as the Temple of Minerva Medica.^[127]

Fluted or coffered domed structures appear in art with greater frequency from the late 4th century.^[128]

The earlychurch of St. John at Ephesus mentioned in a late fourth century account byEtheria appears to have been a timber-roofed cruciform building with arms of roughly equal length and four central piers, each about 3.5 meters by 3.5 meters in section, supporting a crossing dome.^[129]

Emperor Theodosius completed an octagonal domed church dedicated toJohn the Baptist in theHebdomon suburb of Constantinople around 392. It contained the relic of the head of John the Baptist and served as a coronation site for a series of emperors. The remains were destroyed in 1965 and the exact layout is not known, but it may have been a double-shell octagon similar to the Basilica of San Vitale in Ravenna.^[130]

TheChurch of the Holy Sepulchre inJerusalem was likely built with a wooden dome over the shrine by the end of the 4th century.^[131] The rotunda, 33.7 meters (111 ft) in diameter and centered on the tomb ofChrist, consisted of a domed center room surrounded by an ambulatory. The dome rose over a ground floor, gallery, and clerestory and may have had an oculus.^[132] The dome was about 21 meters (69 ft) wide.^[133] Razed to the ground in 1009 bythe Fatimid Caliph, it was rebuilt in 1048 by EmperorConstantine IX Monomachos, reportedly with a mosaic depicting Christ and the Twelve Apostles. The current dome is a 1977 renovation in thin reinforced concrete.^[134]

The so-called baptistery ofSanta Severina inCalabria, southern Italy, was built sometime between the 4th and 11th centuries.^[135]

The largest centrally plannedEarly Christian church, theBasilica of San Lorenzo Maggiore, was built inMilan while that city served as the capital of theWestern Empire and may have been domed with a light material, such as timber or cane.^[136][137] There are two theories about the shape of this dome: a Byzantine-style dome on spherical pendentives with a ring of windows similar to domes of the later Justinian era, or an octagonal cloister vault following Roman trends and like the vaulting over the site's contemporarychapel of Saint Aquiline, possibly built with vaulting tubes, pieces of which had been found in excavations. Although these tubes have been shown to date from a medieval reconstruction, there is evidence supporting the use of Roman concrete in the original.^[138] Alternatively, the central covering may have been a squaregroin vault.^[139] Fires in 1071 and 1075 damaged the building and the central covering collapsed in 1103. It was rebuilt with aRomanesque dome that lasted until 1573, when it collapsed and was replaced by the present structure.^[140] The original vaulting was concealed by a square drum externally rather than the octagon of today, which dates from the 16th century.^[141] The building may have been the church of the nearby imperial palace and a proposed construction between 355 and 374 under theArian bishopAuxentius of Milan, who later "suffered a kind ofdamnatio memoriae at the hands of his orthodox successors", may explain the lack of records about it.^[142] Or it may have been commissioned as a mausoleum byStilicho when he served asregent forHonorius.^[143] Two late medieval texts,Quaternus indulgentiarum (middle of the fourteenth century) and Antonio Confalonieri'sChronica pontificum (early fifteenth century), document a traditional date for the consecration of the church as the year 416.^[144]Thermoluminescence andradiocarbon dating indicate construction began sometime between 390 and 410, using a significant proportion of recycled bricks. TheChapel of San Aquilino was built between 400 and 420.^[145] The brick octagonal cloister vault of the chapel of San Aquilino had one groin reinforced with interlocking amphorae, a fifth century technique.^[146] The chapel of Sant'Ippolito was built with the original building and its dome appears to have used interlocking amphorae, rather than vaulting tubes, but it was rebuilt in 1916.^[147] The dome of the chapel of San Sisto, on the north side of the building, appears to have been first built in the early sixth century as a half-sized copy of San Aquilino, perhaps with a dwarf gallery, but it was rebuilt in the 17th century.^[148]

By the 5th century, structures with small-scale domed cross plans existed across the Christian world. Examples include theMausoleum of Galla Placidia, the martyrium attached to theBasilica of San Simpliciano, and churches inMacedonia and on the coast ofAsia Minor.^[149] In Italy, theBaptistery of San Giovanni in Naples and theChurch of Santa Maria della Croce in Casarano have surviving early Christian domes.^[150] InTolentino, the mausoleum ofCatervus was modeled on the Pantheon, but at one-quarter scale and with three protruding apses, around 390–410. TheBaptistery of Neon in Ravenna was completed in the middle of the 5th century and there were 5th century domes in the baptisteries atPadula andNovara.^[115] Small brick domes are also found in towers ofConstantinople's early 5th century land walls.^[151] Underground cisterns in Constantinople, such as theCistern of Philoxenos and theBasilica Cistern, were composed of a grid of columns supporting small domes, rather thangroin vaults.^[152] The square bay with an overhead sail vault or dome on pendentives became the basic unit of architecture in the early Byzantine centuries, found in a variety of combinations.^[149]

Early examples of Byzantine domes existed over the hexagonal hall of thePalace of Antiochos, the hexagon atGülhane, themartyium of Sts. Karpos and Papylos, and the rotunda at theMyrelaion.^[151] The timber-roofedbasilica of Ilissos [de] in Athens had a dome over its sanctuary.^[153] The 5th centurySt. Mary's church in Ephesus had small rectangular side rooms with sail vaults made of arched brick courses. The brick dome of the baptistery at St. Mary's was composed of a series of tightly archedmeridional sections.^[154] The Church of Saint Simeon Stylites likely had a wooden polygonal dome over its central 27-meter (89 ft) wide octagon.^[155]

In the city of Rome, at least 58 domes in 44 buildings are known to have been built before domed construction ended in the middle of the 5th century.^[156] Although they continued to be built elsewhere in Italy, domes would not be built again within Rome until 1453.^[157] The last imperial domed mausoleum in the city wasthat of Emperor Honorius, built in 415 next toSt. Peter's Basilica. It was demolished in 1519 as part of the rebuilding of St. Peter's, but had a dome 15.7 meters wide and its appearance is known from some images.^[158] The last domed church in the city of Rome for centuries wasSanto Stefano al Monte Celio around 460. It had an unusual centralized plan and a 22 meter wide dome made withvaulting tubes [it], a technique that may have been imported from the new western capital of Ravenna.^[159] Other 5th century Italian domes may includea church at Casaranello [it] (first half of the 5th century), thechapel of San Vittore in Milan [it] at theBasilica of Sant'Ambrogio, the chapel of St. Maria Mater Domini in thechurch of San Felice and Fortunato in Vicenza [it], and Sicily'sCuba [it] of Malvagna (5th or 6th century) and San Pietro ad Baias (5th or 6th century).^[160]

In Jerusalem,Sion Church was built with a wooden dome between 456 and 460.^[161] TheChurch of the Kathisma was built along the road from Jerusalem to Bethlehem around 456 with an octagonal plan. It was built over the site of a rock said to be used as a seat by the Virgin Mary as she traveled to Bethlehem while pregnant with Jesus, corresponding to a story told in theProtoevangelium of James.^[162] The outer diameter was similar to that of the Church of the Holy Sepulchre at 26–27 meters, and the innermost octagon supported a dome 15.5 meters wide.^[163]

There were a half dozen tetraconch-plan buildings built in important cities from Syria to northern Mesopotamia in a 75 year period beginning around 460, with their 10-13 meter central space covered either by a pyramidal roof or a dome made of timber or another light material. Examples were found atSeleucia Pieria (the so-called "martyrion"),Rusafah,Apamea, possibly incorporated into theAl-Halawiyah Madrasa atAleppo, at the site ofSt. Mary Church inDiyarbakır, and the cathedral atBosra.^[164]

With the end of theWestern Roman Empire, domes became a signature feature of the church architecture of the survivingEastern Roman Empire.^[152][165] A transition from timber-roofed basilicas to vaulted churches seems to have occurred there between the late 5th century and the 7th century, with early examples in Constantinople, Asia Minor, andCilicia.^[166] The first known domed basilica may have been a church at Meriamlik in southern Turkey, dated to between 471 and 494, although the ruins do not provide a definitive answer. It is possible earlier examples existed in Constantinople, where it has been suggested that the plan for the Meriamlik church itself was designed, but no domed basilica has been found there before the 6th century.^[167]

The 6th century marks a turning point for domed church architecture. Centrally planned domed churches had been built since the 4th century for very particular functions, such as palace churches or martyria, with a slight widening of use around 500 AD, but most church buildings were timber-roofed halls on the basilica plan.^[168] UnderJustin I in the 520s, Justinian seems to have razed theBasilica of St. John in Ephesus and replaced it with a greek cross cruciform building with five domes similar to his later Church of the Holy Apostles in Constantinople. This version of the building wasdescribed by Procopius inThe Buildings. Justinian would later replace the western arm of this building, likely in the 550s, expanding it from one domed bay to two domed bays.^[169]

TheChurch of St. Polyeuctus in Constantinople (524–527) may have been built as a large and lavish domed basilica similar to the Meriamlik church of fifty years before—and to the laterHagia Irene of Emperor Justinian—byAnicia Juliana, a descendant of the former imperial house, although the linear walls suggest a timber roof, rather than a brick dome.^[167][170] There is a story that she used the contribution to public funds that she had promised Justinian on his ascension to the throne to roof her church in gold.^[171] The church included an inscription praising Juliana for having "surpassed Solomon" with the building, and it may have been with this in mind that Justinian would later say of his Hagia Sophia, "Solomon, I have vanquished thee!".^[172][173]

In the second third of the 6th century, church building by theEmperor Justinian used the domed cross unit on a monumental scale, in keeping with Justinian's emphasis on bold architectural innovation. His church architecture emphasized the central dome and his architects made the domed brick-vaulted central plan standard throughout the Roman east. This divergence with the Roman west from the second third of the 6th century may be considered the beginning of a "Byzantine" architecture.^[174] Timber-roofed basilicas, which had previously been the standard church form, would continue to be so in the medieval west.^[175]

The earliest existing of Justinian's domed buildings may be the central planChurch of Saints Sergius and Bacchus in Constantinople, completed by 536. It is called the "Little Hagia Sophia" mosque today, but may have been begun five years earlier than that building. The dome rests on an octagonal base created by eight arches on piers and is divided into sixteen sections. Those sections above the flat sides of the octagon are flat and contain a window at their base, alternating with sections from the corners of the octagon that are scalloped, creating an unusual kind of pumpkin dome.^[176] Its dates of construction are disputed and may have begun in 532. The alternating scalloped and flat surfaces of the current dome resemble those in Hadrian's half-dome Serapeum in Tivoli, but may have replaced an original drum and dome similar to that over the Basilica of San Vitale in Ravenna.^[177] The building was built within the precinct of thePalace of Hormistas, the residence of Justinian before his ascension to the throne in 527, and includes an inscription mentioning the "sceptered Justinian" and "God-crownedTheodora".^[178]

After theNika Revolt destroyed much of the city of Constantinople in 532, including the churches of Hagia Sophia ("Holy Wisdom") and Hagia Irene ("Holy Peace"), Justinian had the opportunity to rebuild. Both had been basilica plan churches and both were rebuilt as domed basilicas, although the Hagia Sophia was rebuilt on a much grander scale.^[179] Built byAnthemius of Tralles andIsidore of Miletus in Constantinople between 532 and 537, the Hagia Sophia has been called the greatest building in the world. It is an original and innovative design with no known precedents in the way it covers a basilica plan with dome and semi-domes. Periodic earthquakes in the region have caused three partial collapses of the dome and necessitated repairs. The precise shape of the original central dome completed in 537 was significantly different from the current one and, according to contemporary accounts, much bolder.^[180]

Procopius wrote that the original dome seemed "not to rest upon solid masonry, but to cover the space with its golden dome suspended from heaven." Byzantine chroniclerJohn Malalas reported that this dome was 20 byzantine feet lower than its replacement.^[181] One theory is that the original dome continued the curve of the existing pendentives (which were partially reconstructed after its collapse), creating a massive sail vault pierced with a ring of windows.^[182][183] This vault would have been part of a theoretical sphere 46 meters (151 ft) in diameter (the distance of the diagonal of the square bay defined by the pendentives), seven percent greater than the span of the Pantheon's dome.^[184][185] Another theory raises the shallow cap of this dome (the portion above what are today the pendentives) on a relatively short recessed drum containing the windows.^[186] This first dome partially collapsed in 558 due to an earthquake and the design was then revised to the present profile.^[187]Agathias, who likely witnessed both the original dome and its replacement, wrote that the replacement dome "did not strike spectators with as much amazement as before, but it was far more securely set up."^[188] The collapse of the first dome is associated with the piers and buttresses supporting the dome leaning outward in a direction transverse to the nave, due to a combination of thrust from the low dome encountering unsettled mortar from the rapid construction,subsidence in the natural rock foundations, and the 557 earthquake, although the buttresses have been corrected visually on their exterior end walls. This made the rebuilt dome slightly elliptical in plan.^[189] Earthquakes also caused partial collapses of the dome in 989 and 1346, so that the present dome consists of portions dating from the 6th century, on the north and south sides, and portions from the 10th and 14th centuries on the west and east sides, respectively. There are irregularities where these sectors meet.^[190]

The current central dome, above the pendentives, is about 750 millimeters (30 in) thick.^[191] The current dome profile was designed byIsidore the Younger, nephew of the original Isidore, before 563. Repairs completed in 994 were byTrdat ofArmenia. Repairs completed in 1354 were byAstras,Faciolatus, andGiovanni Peralta.^[192] The dome is about 32 meters (105 ft) wide and contains 40 radial ribs that spring from between the 40 windows at its base. Four of the windows were blocked as part of repairs in the 10th century.^[193] The ring of windows at the base of the central dome are in the portion where the greatest hoop tension would have been expected and so they may have been used to help alleviate cracking along the meridians.^[194] Iron cramps between the marble blocks of its cornice helped to reduce outward thrusts at the base and limit cracking, like the wooden tension rings used in other Byzantine brick domes.^[85] The original dome had included wooden tension chains at the base of the windows. Thin iron chains were added to the reconstructed dome at different times during the Byzantine period. Larger tie rods were added under theOttomans in the 16th and 19th centuries.^[195] The dome and pendentives are supported by four large arches springing from four piers. Additionally, two huge semi-domes of similar proportion are placed on opposite sides of the central dome and themselves contain smaller semi-domes between an additional four piers.^[196] The Hagia Sophia, as both the cathedral of Constantinople and the church of the adjacentGreat Palace of Constantinople, has a form of octagonal plan.^[197]

The city of Ravenna, Italy, had served as the capital of the Western Roman Empire after Milan from 402 and the capital of the subsequent kingdoms ofOdoacer andof Theodoric untilJustinian's reconquest in 540. An octagonal building in Ravenna, begun under Theodoric in 525, was completed under the Byzantines in 547 as theBasilica of San Vitale and contains aterracotta dome.^[198] It may belong to a school of architecture from 4th and 5th century Milan.^[199] The building is similar to the Byzantine Church of Saints Sergius and Bacchus and the laterChrysotriklinos, or throne hall and palace church of Constantinople, and it would be used as the model forCharlemagne's palace chapel atAix-la-Chapelle.^[200] Hollowamphorae were fitted inside one another to provide a lightweight structure for the dome and avoid additional buttressing.^[201] It is 18 meters (59 ft) in diameter.^[15] The amphorae were arranged in a continuous spiral, which required minimal centering and formwork but was not strong enough for large spans.^[90] The dome was covered with a timber roof, which would be the favored practice for later medieval architects in Italy although it was unusual at the time.^[201]

In Constantinople, Justinian also tore down the aging Church of the Holy Apostles andrebuilt it on a grander scale between 536 and 550.^[202] The original building was acruciform basilica with a central domed mausoleum. Justinian's replacement was apparently likewise cruciform but with a central dome and four flanking domes. The central dome over thecrossing had pendentives and windows in its base, while the four domes over the arms of the cross had pendentives but no windows.^[203] The domes appear to have been radically altered between 944 and 985 by the addition of windowed drums beneath all five domes and by raising the central dome higher than the others.^[204] The second most important church in the city after the Hagia Sophia, it fell into disrepair after theLatin occupation of Constantinople between 1204 and 1261 and it was razed to the ground byMehmed the Conqueror in 1461 to build hisFatih Mosque on the site.^[205] Justinian'sBasilica of St. John at Ephesus and Venice'sSt Mark's Basilica are derivative of Holy Apostles.^[203] More loosely, theCathedral of St. Front and theBasilica of Saint Anthony of Padua are also derived from this church.^[206]

Italian church architecture from the late sixth century to the end of the eighth century was influenced less by the trends of Constantinople than by a variety of Byzantine provincial plans.^[207] The sacristy of theBasilica of Saints Felice and Fortunato [it] inVicenza, Italy, is part of an older cruciform domed church built by GeneralNarses in 554. The style of the church was characteristic of the Byzantine churches of Ravenna.^[121] Other 6th century domes in Italy include those ofthe baptistery of Canosa di Puglia [it], theBasilica of San Leucio atCanosa,the baptistery of Nocera Superiore [it], and theSanctuary of San Prosdocimo in theAbbey of Santa Giustina inPadua.^[115]

Justinian and his successors modernized frontier fortifications throughout the century. The example atQasr ibn Wardan (564) in the desert of eastern Syria is particularly impressive, containing a governor's palace, barracks, and a church built with techniques and to plans possibly imported from Constantinople.^[208] The church dome is unusual in that the pendentives sprang from an octagonal drum, rather than the four main arches, and in that it was made of brick, which was rare in Syria.^[151]

The Golden Triclinium, or Chrysotriklinos, of the Great Palace of Constantinople served as an audience hall for the Emperor as well as a palace chapel. Nothing of it has survived except descriptions, which indicate that it had a pumpkin dome containing sixteen windows in its webs and that the dome was supported by the arches of eight niches connecting to adjoining rooms in the building's likely circular plan.^[209] Alternatively, the building may have been octagonal in plan, rather than circular.^[210] The building was not free-standing and was located at the intersection of the public and private parts of the palace. Smaller windows filled with thin sheets ofalabaster may have existed over each of the curtain-covered side niches and below the cornice at the base of the dome.^[211] The dome seems to have had webs that alternated straight and concave, like those of the dome of Justinian's Church of Saints Sergius and Bacchus, and may have been built about 40 years after that church.^[212] It was begun underEmperor Justin II, completed by his successorTiberius II, and continued to be improved by subsequent rulers. It was connected to the imperial living quarters and was a space used for assembly before religious festivals, high promotions and consultations, as a banqueting hall, a chapel for the emperor, and a throne room. Never fully described in any of its frequent mentions in Byzantine texts, the room was restricted to members of the court and the "most highly rated foreigners". In the 10th century, the throne in the east niche chamber was directly below anicon of anenthroned Christ.^[213]

Other 6th century examples of domed constructions may includeNostra Segnora de Mesumundu inSiligo,Sardinia (before 534),Sant’Angelo inPerugia,San Miserino [it] nearSan Donaci (6th or 7th century), and the Trigona of Cittadella nearNoto (6th or 7th century).^[160] TheBasilica of San Saturnino in Sardinia was built in the 6th century as a Greek-cross martyrium with a central dome.^[214]

The period ofIconoclasm, roughly corresponding to the 7th to 9th centuries, is poorly documented but can be considered a transitional period.^[215] Thecathedral of Sofia has an unsettled date of construction, ranging from the last years of Justinian to the middle of the 7th century, as theBalkans were lost to theSlavs andBulgars. It combines a barrel-vaulted cruciform basilica plan with acrossing dome hidden externally by the drum. It resembles some Romanesque churches of later centuries, although the type would not be popular in later Byzantine architecture.^[216]

Destruction by earthquakes or invaders in the seventh to ninth centuries seems to have encouraged the development of masonry domes and vaulting experimentation over basilicas inAnatolia. TheSivrihisar Kizil Kilise has a dome over an octagonal drum with windows on a square platform and was built around 600, before the battles in the region in the 640s. The domedChurch of Mary in Ephesus may have been built in the late sixth or first half of the seventh century with reused bricks. The smallerChurch of the Dormition of the Monastery of Hyacinth [ru] inNicaea had a dome supported on four narrow arches and dates prior to 727. The lobed dome of the Church of St. Clement atAncyra was supported by pendentives that also included squinch-like arches, a possible indication of unfamiliarity with pendentives by the builders. The upper portion of theChurch of St. Nicholas at Myra was destroyed, but it had a dome on pendentives over the nave that might have been built between 602 and 655, although it has been attributed to the late eighth or early ninth centuries.^[217]

TheChurch of Santa Maria di Gallana [it] in Agro diOria was built sometime between 668 and the 9th century.^[135]

Part of the fifth-century basilica of St. Mary at Ephesus seems to have been rebuilt in the eighth century as a cross-domed church, a development typical of the seventh to eighth centuries and similar to the cross-domed examples ofHagia Sophia in Thessaloniki,St. Nicholas at Myra, St. Clement's atAnkara, and the church of theKoimesis atNicaea.^[218]

With the decline in the empire's resources followinglosses in population andterritory, domes in Byzantine architecture were used as part of more modest new buildings. The large-scale churches of Byzantium were, however, kept in good repair. The upper portion of the Church of Hagia Irene was thoroughly rebuilt after the740 Constantinople earthquake. The nave was re-covered with an elliptical domical vault hidden externally by a low cylinder on the roof, in place of the earlier barrel vaulted ceiling, and the original central dome from the Justinian era was replaced with one raised upon a high windowed drum. The barrel vaults supporting these two new domes were also extended out over the side aisles, creating cross-domed units.^[219] By bracing the dome with broad arches on all four sides, the cross-domed unit provided a more secure structural system.^[215] These units, with most domes raised on drums, became a standard element on a smaller scale in later Byzantine church architecture, and all domes built after the transitional period were braced with bilateral symmetry.^[220] The dome over theChurch of the Archangels [tr] atSige was replaced in the 19th century, but the original was dated in the 18th century to 780.^[221]

A small, unisex monastic community inBithynia, near Constantinople, may have developed thecross-in-square plan church during the Iconoclastic period, which would explain the plan's small scale and unifiednaos. The ruined church of St. John atPelekete Monastery is an early example.^[222] Monks had supported the use of icons, unlike the government-appointedsecular clergy, and monasticism would become increasingly popular. A new type of privately funded urban monastery developed from the 9th century on, which may help to explain the small size of subsequent building.^[223]

The church architecture of Sicily has few examples from the Byzantine period, having beenconquered by Muslims in 827, but quincunx churches exist with single domes on tall central drums and either Byzantine pendentives or Islamic squinches.^[224] Very little architecture from the Islamic period survives on the island, either.^[225]

Venice's architecture was a blend of Byzantine and northern Italian influences, although nothing from the ninth and tenth centuries has survived except the foundations of the firstSt. Mark's Basilica.^[226] This building was presumably similar to Justinian's Church of the Holy Apostles based on its layout, but how it was roofed is unknown.^[227]

Timber-roofed basilicas, which had been the standard form until the 6th century, would be displaced by domed churches from the 9th century onward.^[175] In theMiddle Byzantine period (c. 843 – 1204), domes were normally built to emphasize separate functional spaces, rather than as the modular ceiling units they had been earlier.^[228][215] Resting domes on circular or polygonal drums pierced with windows eventually became the standard style, with regional characteristics.^[229]

Single and multi-domed basilicas on Cyprus proposed to date from the ninth or tenth centuries include theChurch of Saint Photios of Gialousa (Karpasia), theChurch of Saint George of Afentrika (Karpasia), theMonastery of Saint Barnabas (Salamis), theChurch of Saint Paraskeva [ru] (Geroskipou), and theChurch of Saints Hilarion and Barnabas [de] (Peristerona).^[230]

The cross-in-square plan, with a single dome at the crossing or five domes in aquincunx pattern, became widely popular in the Middle Byzantine period.^[231] Examples include an early 9th century church inTirilye, now called theFatih Mosque.^[232] TheNea Ekklesia of EmperorBasil I was built in Constantinople around 880 as part of a substantial building renovation and construction program during his reign. It had five domes, which are known from literary sources, but different arrangements for them have been proposed under at least four different plans. One has the domes arranged in a cruciform pattern like those of the contemporaneous Church of St. Andrew atPeristerai or the much older Church of the Holy Apostles in Constantinople. Others arrange them in a quincunx pattern, with four minor domes in the corners of a square and a larger fifth in the center, as part of a cross-domed or cross-in-square plan.^[233] It is often suggested that the five-domed design ofSt. Panteleimon at Nerezi, from 1164, is based on that of the Nea Ekklesia.^[234]

A 15th-century account of a Russian traveler to Constantinople mentions an abandoned hall from the reign ofLeo VI the Wise, presumably domed, "in which the sun, the moon, and the stars succeeded each other as in heaven."^[235][236]

In the Middle Byzantine period, more complex plans emerge, such as the integrated chapels ofTheotokos of Lips, a monastic church in Constantinople that was built around 907. It included four small chapels on its second floor gallery level that may have been domed.^[237]

The cross-in-square is the most common church plan from the 10th century until thefall of Constantinople in 1453.^[238] This type of plan, with four columns supporting the dome at the crossing, was best suited for domes less than 7 meters (23 ft) wide and, from the 10th to the 14th centuries, a typical Byzantine dome measured less than 6 meters (20 ft) in diameter. For domes beyond that width, variations in the plan were required such as using piers in place of the columns and incorporating further buttressing around the core of the building.^[239]

The palace chapel of the Myrelaion in Constantinople was built around 920 as a cross-in-square church and remains a good example. The earliest cross-in-square in Greece is the Panagia church at the monastery ofHosios Loukas, dated to the late 10th century, but variations of the type can be found from southern Italy to Russia and Anatolia. They served in a wide variety of church roles, including domestic, parish, monastic, palatial, and funerary.^[237]

The distinctive rippling eaves design for the roofs of domes began in the 10th century. In mainland Greece, circular or octagonal drums became the most common.^[229]

In southern Italy, examples include the 8th or 10th centuryTempietto di Seppannibale [it], the 10th centurychurch of San Giorgio dei Martiri [it], and the 10th centurychurch of San Pietro in Otranto [it].^[135] That southern Italy was reconquered andruled by a Byzantine governor from about 970 to 1071 explains the relatively large number of small and rustic Middle Byzantine-style churches found there, including theCattolica inStilo and S. Marco inRossano. Both are cross-in-square churches with five small domes on drums in a quincunx pattern and date either to the period of Byzantine rule or after.^[240]

In Constantinople, drums with twelve or fourteen sides were popular beginning in the 11th century.^[229] The 11th century rock-cut churches of Cappadocia, such asKaranlik Kilise and Elmali Kilise in Göreme, have shallow domes without drums due to the dim natural lighting of cave interiors.^[241]

The domed-octagon plan is a variant of the cross-in-square plan.^[223] The earliest extant example is thekatholikon at the monastery of Hosios Loukas, with a 9-meter (30 ft) wide dome built in the first half of the 11th century.^[242] This hemispherical dome was built without a drum and supported by a remarkably open structural system, with the weight of the dome distributed on eight piers, rather than four, and corbelling used to avoid concentrating weight on their corners. The use of squinches to transition from those eight supports to the base of the dome has led to speculation of a design origin in Arab, Sasanian, or Caucasian architecture, although with a Byzantine interpretation. Similar openness in design was used in the earlier Myrelaion church, as originally built, but the katholikon of Hosios Loukas is perhaps the most sophisticated design since the Hagia Sophia.^[243] The smallermonastic church at Daphni, c. 1080, uses a simpler version of this plan.^[244]

The katholikon ofNea Moni, a monastery on the island ofChios, was built some time between 1042 and 1055 and featured a nine sided, ribbed dome rising 15.62 meters (51.2 ft) above the floor (this collapsed in 1881 and was replaced with the slightly taller present version). The transition from the square naos to the round base of the drum is accomplished by eight conches, with those above the flat sides of the naos being relatively shallow and those in the corners of the being relatively narrow. The novelty of this technique in Byzantine architecture has led to it being dubbed the "island octagon" type, in contrast to the "mainland octagon" type of Hosios Loukas. Speculation on design influences have ranged from Arab influence transmitted via the recently built domed octagon chapels at the Church of the Holy Sepulchre in Jerusalem or theAl-Hakim Mosque in Islamic Cairo, to Caucasian buildings such as theArmenian Cathedral of the Holy Cross. Later copies of the Nea Moni, with alterations, include the churches ofAgios Georgios Sykousis [el], Agioi Apostoli atPyrghi,Panagia Krina [el], and theChurch of the Metamorphosis [mk] inChortiatis.^[245]

The 11th centuryEski İmaret Camii, which may have been the katholikon of the Monastery of Christ Pantepoptēs, and theVefa Kilise Camii (11th or 12th century) included domes over the central bay of their narthexes, which may have indicated imperial patronage.^[246]

The cross-in-square katholikon ofKaisariani Monastery in Athens was built from the end of the 11th to the beginning of the 12th centuries. Its central dome is supported on four marble pillars. A narthex with a lower central dome was added in the 16th or 17th century.^[247]

The larger scale of some Byzantine buildings of the 12th century required a more stable support structure for domes than the four slender columns of the cross-in-square type could provide. The Byzantine churches today calledKalenderhane Mosque,Gül Mosque, and theEnez Fatih mosque all had domes greater than 7 meters (23 ft) in diameter and used piers as part of large cruciform plans, a practice that had been out of fashion for several centuries. A variant of the cross-in-square, the "so-called atrophied Greek cross plan", also provides greater support for a dome than the typical cross-in-square plan by using four piers projecting from the corners of an otherwise square naos, rather than four columns. This design was used in the Chora Church of Constantinople in the 12th century after the previous cross-in-square structure was destroyed by an earthquake.^[248]

The 12th centuryPantokrator monastic complex (1118–36) was built with imperial sponsorship as three adjoining churches.^[249] The south church, a cross-in-square, has a ribbed dome over the naos, domical vaults in the corners, and a pumpkin dome over the narthex gallery. The north church is also a cross-in-square plan. The middle church, the third to be built, fills the long space between the two earlier churches with two oval domes of the pumpkin and ribbed types over what appear to be separate functional spaces. The western space was an imperial mausoleum, whereas the eastern dome covered a liturgical space.^[250]

There is a written account byNicholas Mesarites of a Persian-style muqarnas dome built as part of a late 12th century imperial palace in Constantinople.^[235] Called the "Mouchroutas Hall", it may have been built as part of an easing in tensions between the court ofManuel I Komnenos andKilij Arslan II of theSultanate of Rum around 1161, evidence of the complex nature of the relations between the two states. The account, written byNicholas Mesarites shortly before theFourth Crusade, is part of a description of the coup attempt byJohn Komnenos in 1200, and may have been mentioned as a rhetorical device to disparage him.^[251] The domed Mouchroutas was built next to the Byzantine throne room at the imperial palace while a Rum Seljuk prince was living there and may have been used as a reception hall.^[252]

The Late Byzantine Period, from 1204 to 1453, has an unsettled chronology of buildings, especially during theLatin Occupation. The fragmentation of the empire,beginning in 1204, is reflected in a fragmentation of church design and regional innovations.^[253]

The church ofHagia Sophia in theEmpire of Trebizond dates to between 1238 and 1263 and has a variation on the quincunx plan. Heavy with traditional detailing from Asia Minor, and possiblyArmenian orGeorgian influence, the brick pendentives and drum of the dome remain Byzantine.^[254]

After 1261, new church architecture in Constantinople consisted mainly of additions to existing monastic churches, such as theMonastery of Lips andPammakaristos Church, and as a result the building complexes are distinguished in part by an asymmetric array of domes on their roofs. This effect may have been in imitation of the earlier triple-church Pantokrator monastic complex.^[255]

In theDespotate of Epirus, theChurch of the Parigoritissa (1282–9) is the most complex example, with a domed octagon core and domed ambulatory.^[256] Columns beneath the dome rest on cantilevered supports and large wooden tie-beams have remained in place to ensure stability. Its eccentric design results in a very high dome with a steep viewing angle, which may explain the unusually large Pantokrator image on the dome.^[257] Built in the capital ofArta, its external appearance resembles a cubic palace. The upper level narthex and galleries have five domes, with the middle dome of the narthex an open lantern. This Greek-cross octagon design, similar to the earlier example at Daphni, is one of several among the various Byzantine principalities. Another is found in the Hagia Theodoroi at Mistra (1290–6).^[258]

Churches in Epirus with domed narthexes includedSt. Theodora in Arta [el] (second half of the 13th century),Panagia Vlacherna (narthex added after 1284), andPanagia Vellas (1295-1296).^[259] Another church with a domed narthex was theChurch of the Virgin Peribleptos in Ohrid (1294-1295).^[260]

Churches with domed narthexes include theHoly Trinity in Berat (late 13th to early 14th century), theChurch of St. Demetrius in Kypseli [mk] (probably after 1306), and the church ofSt. George in Omorphoklisia (c. 1295–1317).^[260]

Mistra was ruled from Constantinople after 1262, then was thesuzerain of theDespotate of the Morea from 1348 to 1460.^[261] In Mistra, there are several basilica plan churches with domed galleries that create a five-domed cross-in-square over a ground-level basilica plan. The Aphentiko atBrontochion Monastery was built c. 1310–22 and the later church of thePantanassa Monastery (1428) is of the same type.^[256] Both churches have domes over their western galleries, suggesting a role for those galleries in appearances by members of the local court.^[262] The Aphentiko may have been originally planned as a cross-in-square church, but has a blend of longitudinal and central plan components, with an interior divided into nave and aisles like a basilica. The barrel-vaulted nave and cross arms have a dome at their crossing, and the corner bays of the galleries are also domed to form a quincunx pattern. A remodeling of the Metropolis church in Mistra created an additional example. The Pantanassa incorporates Western elements in that domes in its colonnaded porch are hidden externally, and its domes have ribs of rectangular section similar to those ofSalerno,Ravello, andPalermo.^[263] The fresco of the dome ofPeribleptos Monastery is from about 1370 and features a small Pantokrator image.^[264]

InThessaloniki, a distinctive type of church dome developed in the first two decades of the 14th century. It is characterized by a polygonal drum with rounded colonnettes at the corners, all brick construction, and faces featuring three arches stepped back within one another around a narrow "single-light window".^[265] One of the hallmarks of Thessalonian churches was the plan of a domed naos with aperistoon wrapped around three sides.^[266] The churches ofHagios Panteleimon,Hagia Aikaterine, andHagioi Apostoloi have domes on these ambulatoryporticoes.^[256] The five domes of the Hagioi Apostoloi, or Church of the Holy Apostles, in Thessaloniki (c. 1329) makes it an example of a five-domed cross-in-square church in the Late Byzantine style.^[238]

Constantinople's cultural influence extended from Sicily to Russia.^[267]Armenia, as a border state between the Roman-Byzantine and Sasanian empires, was influenced by both.^[268] The exact relationship between Byzantine architecture and that of theCaucasus is unclear.Georgia and Armenia produced many central planned, domed buildings in the 7th century and, after a lull during the Arab invasions, the architecture flourished again in the Middle Byzantine Period.^[215]

Armenian church domes were initially wooden structures.Etchmiadzin Cathedral (c. 483) originally had a wooden dome covered by a wooden pyramidal roof before this was replaced with stone construction in 618. Churches with stone domes became the standard type after the 7th century, perhaps benefiting from a possible exodus ofstonecutters from Syria, but the long traditions of wooden construction carried over stylistically. Some examples in stone as late as the 12th century are detailed imitations of clearly wooden prototypes.^[269]

Armenian church building was prolific in the late 6th and 7th centuries and, by the 7th century, the churches tend to be either central plans or combinations of central and longitudinal plans. Domes were supported by either squinches (which were used in the Sasanian Empire but rarely in the Byzantine) or pendentives like those of the Byzantine empire, and the combination of domed-cross plan with the hall-church plan could have been influenced by the architecture of Justinian. Domes and cross arms were added to the longitudinalcathedral of Dvin from 608 to 615 and achurch in Tekor. Other domed examples includePtghnavank inPtghni (c. 600), achurch in T'alinn (662-85), theCathedral of Mren (629-40), and theMastara Church (9th and 10th centuries).^[270][271]

An 11th-century Armenian source names an Armenian architect,Trdat, as responsible for the rebuilding of the dome of Hagia Sophia in Constantinople after the 989 earthquake caused a partial collapse of the central dome. Although squinches were the more common supporting system used to support Armenian domes, pendentives are always used beneath the domes attributed to Trdat, which include the 10th-century monasteries ofMarmasen,Sanahin, andHelpat, as well as the patriarchal cathedral ofArgina (c. 985), theCathedral of Ani (989-1001), and the palace chapel ofKing Gagik II (c. 1001–1005).^[272]

TheThrone Hall of Dongola, built in the 9th century atOld Dongola, was used by the kings ofMakuria, the most powerful kingdom in medieval Africa, for 450 years until 1317. The upper floor contained a likely cruciform room with a small dome at the center, in imitation of the audience halls of the Byzantine emperors. Bulgarian tsars had similar halls.^[273]

Similarities to the architecture of Armenia and the "Eastern Christian world" have been noted for thearchitecture of early Croatia, from about 800 to 1100, along with similarities with westernPre-Romanesque architecture.^[274] In the Balkans, where Byzantine rule weakened in the 7th and 8th centuries, domed architecture may represent Byzantine influence or, in the case of the centrally planned churches of 9th-centuryDalmatia, the revival of earlier Roman mausoleum types. An interest in Roman models may have been an expression of the religious maneuvering of the region between the Church of Constantinople and that of Rome. Examples include the Church of Sv. Luka inKotor, theChurch of Sv. Trojce near Split, and the early 9th centuryChurch of Sv. Donat inZadar. The Church of Sv. Donat, originally domed, may have been built next to a palace and resembles palace churches in the Byzantine tradition.^[275] The ruins at thechurch of St. Mary on the Island [hr] inSolin (before 976) may have had a dome over its square bay.^[276] TheChurch of St. Peter on Priko [hr] (c. 1050-1075) includes a dome on pendentives in its central bay. It is hidden on the exterior by a square turret with a pyramidal roof.^[277] The chapel of St. Nicholas (c. 1100) on the island ofLopud is similar to the Church of St. Peter on Priko and includes a dome over its central bay.^[278]

The architectural chronology of the central and eastern Balkans is unsettled during the period of theFirst Bulgarian Empire, in part because of similarity between Justinian-era churches from the 6th century and what may have been a revival of that style in the late 9th and early 10th centuries under theChristianized Bulgarian tsars. Remains of theRound Church inPreslav, a building traditionally associated with the rule ofTsar Simeon (893–927), indicate that it was a domed palace chapel. Its construction features, however, resemble instead 3rd and 4th century Roman mausolea, perhaps due to the association of those structures with the imperial idea.^[279]

InDalmatia, a group of six lobed centralized buildings similar to antique models are known from the 9th to the 11th centuries: inBrnazi,Pridraga,Split,Oslje,Zara, andTrogir.^[280]

Byzantine architecture was introduced to theRus' people in the 10th century, with churches after the conversion ofPrince Vladimir of Kiev being modeled after those of Constantinople, but made of wood. The Russianonion dome was a later development.^[281] The earliest architecture ofKiev, the vast majority of which was made of wood, has been lost to fire, but by the 12th century masonry domes on low drums in Kiev andVladimir-Suzdal were little different than Byzantine domes, although modified toward the "helmet" type with a slight point. TheCathedral of St. Sophia in Kiev (1018–37) was distinctive in having thirteen domes, forJesus and theTwelve Apostles, but they have since been remodeled in theBaroque style and combined with an additional eight domes.^[282] The pyramidal arrangement of the domes was a Byzantine characteristic, although, as the largest and perhaps most important 11th century building in the Byzantine tradition, many of the details of this building have disputed origins.^[283]

Bulbous onion domes on tall drums were a development of northern Russia, perhaps due to the demands of heavy ice and snowfall along with the more rapid innovation permitted by theNovgorod region's emphasis on wooden architecture. The central dome of theCathedral of St. Sophia (1045–62) in Novgorod dates from the 12th century and shows a transitional stage. Other churches built around this time are thoseof St. Nicholas (1113), theNativity of the Virgin (1117), andSt. George (1119–30).^[284]

Eastern European and Orthodox examples

Saint Nicholas Cathedral, Novgorod

Church of Christ Pantocrator, Nesebar, Bulgaria

Ravanica Monastery,Serbia

Cathedral of the Assumption,Moscow

In Romanesque Italy, Byzantine influence can most clearly be seen in Venice's St Mark's Basilica, from about 1063, but also in the domed churches of southern Italy, such asCanosa Cathedral [it] (1071^[285] or 6th century^[286]) and theold Cathedral of Molfetta [it] (c. 1160).^[285]

InNorman Sicily, architecture was a fusion of Byzantine, Islamic, and Romanesque forms, but the dome of thePalatine Chapel (1132–43) atPalermo was decorated with Byzantine mosaic, as was that of the church ofSanta Maria dell'Ammiraglio (1140s).^[287]

The unusual use ofdomes on pendentives in a series of seventy Romanesque churches in theAquitaine region of France strongly suggests a Byzantine influence. St. Mark's Basilica was modeled on the now-lost Byzantine Church of the Holy Apostles in Constantinople, andPérigueux Cathedral in Aquitaine (c. 1120) likewise has five domes on pendentives in a Greek cross arrangement.^[288] Other examples include the domed naves ofAngoulême Cathedral (1105–28),Cahors Cathedral (c. 1100–1119), and theAbbey church of Sainte-Marie in Souillac [fr] (c. 1130).^[289]

Byzantium's neighboringOrthodox powers in Europe emerged as architectural centers in their own right during the Late Byzantine Period. TheBulgarian churches ofNesebar are similar to those in Constantinople at this time.^[256] The style and vaulting in the Nesebar cross-in-square churches ofChrist Pantocrator andSt John Aliturgetos, for example, are similar to examples in Constantinople.^[290]

TheGračanica monastery is an example of a five-domed cross-in-square church in the Late Byzantine style, built around 1311 inSerbia.^[238] The architect and artisans of the Gračanica monastery church probably came from Thessaloniki and its style reflects Byzantine cultural influence.^[291] The church has been said to represent "the culmination of Late Byzantine architectural design."^[256] Following the construction of Gračanica monastery, the architecture of Serbia used the "so-called Athonite plan", for example atRavanica (1375–7).^[256] Domes over an entranceway were royal markers. An example is the Serbian reconstruction of the katholikon of the Monastery ofHilandar (1312-1316), which included a domical vault over the central eastern bay of the narthex.^[292] The church of St. Nicholas of Dabar atBanja Monastery (1329) has the earliest example in Serbia of a dome over a narthex, similar to Byzantine examples from theDespotate of Epirus.^[293]Serbian churches included domes in the Byzantine style around the 1330s and they increased in use through the period of theSerbian Empire.^[294]

In Romania,Wallachia was influenced by Serbian architecture andMoldavia was more original, such as in theVoroneț Monastery with its small dome.^[256]

Moscow emerged as the most important center of architecture following the fall of Constantinople in 1453.^[295] TheCathedral of the Assumption (1475–79), built in the Kremlin to house theicon ofOur Lady of Vladimir, was designed in a traditional Russian style by an Italian architect.^[296]

Italian Renaissance architecture combined Roman and Romanesque practices with Byzantine structures and decorative elements, such as domes with pendentives over square bays.^[297][298] TheCassinese Congregation used windowed domes in the Byzantine style, and often also in a quincunx arrangement, in their churches built between 1490 and 1546, such as theAbbey of Santa Giustina.^[299]

The technique of using wooden tension rings at several levels within domes and drums to resist deformation, frequently said to be a later invention ofFilippo Brunelleschi, was common practice in Byzantine architecture.^[23] The technique of using double shells for domes, although revived in the Renaissance, originated in Byzantine practice.^[300]

The dome of the Pantheon, as a symbol of Rome and its monumental past, was particularly celebrated and imitated, although copied only loosely. Studied in detail from the early Renaissance on, it was an explicit point of reference for the dome ofSt. Peter's Basilica and inspired the construction of domed rotundas with temple-front porches throughout western architecture into the modern era. Examples includePalladio's chapel at Maser (1579–80),Bernini's church ofS. Maria dell'Assunzione (1662-4), theLibrary Rotunda of the University of Virginia (1817–26), and thechurch of St. Mary inMalta (1833–60).^[301] Other examples include the church ofSan Simeone Piccolo in Venice (1718–38), the church ofGran Madre di Dio in Turin (1818–31), and the church ofSan Francesco di Paola, Naples in Naples (19th century).^[302]

Ottoman architecture adopted the Byzantine dome form and continued to develop it.^[303] One type of mosque was modeled after Justinian's Church of Sergius and Bacchus with a dome over an octagon or hexagon contained within a square, such as theÜç Şerefeli Mosque (1437–47).^[304] The dome and semi-domes of the Hagia Sophia, in particular, were replicated and refined. A "universal mosque design" based upon this development spread throughout the world.^[305] The first Ottoman mosque to use a dome and semi-dome nave vaulting scheme like that of Hagia Sophia was themosque of Beyazit II. Only two others were modeled similarly:Kılıç Ali Pasha Mosque and theSüleymaniye Mosque (1550–57). Other Ottoman mosques, although superficially similar to Hagia Sophia, have been described as structural criticisms of it. WhenMimar Sinan set out to build a dome larger than that of Hagia Sophia withSelimiye Mosque (1569–74), he used a more stable octagonal supporting structure.^[306] The Selimiye Mosque is of the type originating with the Church of Sergius and Bacchus. Three other Imperial mosques in Istanbul built in this "Classical Style" of Hagia Sophia include four large semi-domes around the central dome, rather than two:Şehzade Camii,Sultan Ahmed I Camii (completed in 1616), and the last to be built:Yeni Cami (1597–1663).^[307]

Western European and Ottoman examples

St Mark's Basilica,Venice

Süleymaniye Mosque,Istanbul

St. Peter's Basilica,Rome

Sultan Ahmed Mosque,Istanbul

AByzantine revival style of architecture occurred in the 19th and 20th centuries. An early example ofthe revival style in Russia was theCathedral of Christ the Saviour (1839–84), which was approved by theTsar to be a model for other churches inthe empire.^[308] The style's popularity spread through scholarly publications produced after theindependence of Greece and the Balkans from the Ottoman Empire.^[309] It was used throughout Europe and North America, peaking in popularity between 1890 and 1914. The Greek OrthodoxSt Sophia's Cathedral (1877–79) and Roman CatholicWestminster Cathedral (begun 1895), both in London, are examples. The throne room ofNeuschwanstein Castle (1885–86) was built byKing Ludwig II in Bavaria.^[310] In the late 19th century, the Hagia Sophia became a widespread model forGreek Orthodox churches.^[305] In southeastern Europe, monumental national cathedrals built in the capital cities of formerly Ottoman areas used Neo-Classical or Neo-Byzantine styles.Sofia's Alexander Nevsky Cathedral andBelgrade's Church of Saint Sava are examples, and used Hagia Sophia as a model due to their large sizes.^[311] Synagogues in the United States were built in a variety of styles, as they had been in Europe (and often with a mixture of elements from different styles), but the Byzantine Revival style was the most popular in the 1920s. Domed examples includeThe Temple of Cleveland (1924), the synagogue ofKAM Isaiah Israel (1924) in Chicago, based upon San Vitale in Ravenna and Hagia Sophia in Istanbul, and the synagogue ofCongregation Emanu-El (1926) in San Francisco.^[312]

In the United States, Greek Orthodox churches beginning in the 1950s tended to use a large central dome with a ring of windows at its base evocative of the central dome of Hagia Sophia, rather than more recent or more historically common Byzantine types, such as the Greek-cross-octagon or five-domed quincunx plans. Examples includeAnnunciation Greek Orthodox Church, completed in 1961 but designed byFrank Lloyd Wright in 1957,Ascension Greek Orthodox Cathedral of Oakland (1960), andAnnunciation Greek Orthodox Cathedral in Atlanta (1967).^[313] The use of a large central dome in American Greek Orthodox churches continued in the 1960s and 1970s before moving toward smaller Middle Byzantine domes, or versions ofEarly Christian basilicas.^[314]

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