TheAqua Anio Vetus was aRoman aqueduct, commissioned in 272 BC by censorManius Curius Dentatus and funded from the war booty seized after the victory againstPyrrhus of Epirus[1]: 29 [2]: 148 .
The aqueduct was 64 km (40 mi) long[3]: 347 , approximately four times as long asAqua Appia, and its discharge of 175,920 m3 (46,470,000 US gal)[3]: 347 over twice as large as the discharge of Aqua Appia. Its source is also much higher than the intake of Aqua Appia[citation needed][4]: §6–20 and it supplied water to higher elevations of the city[citation needed].
The intake of aqueduct was river Anio[2]: 148 , the water being taken directly from the river, and this made the water both muddy and discolored[4]: §15 [3]: 121 [1]: 30 . Because of low water quality, the water from the aqueduct was not used for drinking in later times[1]: 31 .
The aqueduct acquired the nickname ofVetus ("old") only after theAnio Novus was built almost three centuries later.[4]: §13
Constructing the aqueduct took over three years, and it was not finished until aduumviri (a committee of two) was appointed by the Senate to complete the works[1]: 29 . The appointees were the former cencor Curius, who had commissioned the aqueduct in the first place, andFlavius Flaccus[1]: 29 [2]: 148 -- since Curius died only five days after his appointment, the honor of actually finishing the construction ofAnio Vetus went to Flaccus[1]: 29 [2]: 148 .
Its source is believed to be betweenVicovaro andMandela, 850 m (2,790 ft) upstream of the gorge at theConvent of San Cosimato, nearVicovaro.[5] Like the Aqua Appia, its route was mainly underground, but it emerged at many points to cross river valleys especially after bridges using better technology were later used to shorten its course considerably.
It descended from its source along the valley toTivoli, where it left the Anio towards theAlban Hills to nearGallicano, belowPalestrina. It crossed under theVia Latina near the seventh milestone and at the fourth milestone turned northwest to enter Rome.
It entered the city underground at thePorta Praenestina and terminated inside thePorta Esquilina. Only 5.8% of the Vetus' total flow supplied imperial buildings,[4]: §6–20 an important difference from the Appia, which provided almost 22% to such buildings.
It had 35castella for distribution in the city.[4]: §80
Three major restorations were done along with the Appia aqueduct: in 144 BC by the praetorQuintus Marcius Rex during construction of the Aqua Marcia, by adding a secondary conduit in the Casal Morena area and other improvements; in 33 BC whenAgrippa took control of the entire water system of the city; and between 11 and 4 BC byAugustus. With this latter, an underground branch was built, thespecus Octavianus, that started from the current Pigneto area and followed theVia Casilina and reached the area where theBaths of Caracalla were later built.
Other restorations in the first two centuries AD include the construction of bridges across valleys on the route to shortcut long underground diversions.
Remains of several bridges still exist: Ponte Della Mola, Ponte Taulella,[6] and Ponte Pischero.[7]
The Ponte della Mola is one of the most majestic aqueduct bridges[8] and is located near the village of San Vittorino. It crosses the Mola stream with a series of 22 arches mostly in two-tier arrangement over a length of 155 m (509 ft) and a height of 24.5 m (80 ft).[9] Earlier routes of the aqueduct passed over two other bridges starting higher upstream which were successively abandoned when they became excessively damaged.Hadrian built the bridge also to shorten the route by about 1.5 km (0.93 mi).
The bridge is made of Roman concrete covered withopus reticulatum with the use oftufa blocks in the abutments and brickwork for the arch. It has a notable asymmetry due to the connection with the original channels at each end which were of widely different levels at this point in the valley as they previously followed a long loop. Therefore the moderate slope of 1.1 m over 142 m of length (3½ ft over 466 ft) (0.77%) of the first 18 arches was followed by the considerable slope of 4.1 m over 25 m (13 ft over 82 ft) (16.3%) of the last four arches, as it was safer to lose energy in a short waterfall.[10]
The central part, a stretch of three double arches, collapsed in 1965 and an adjacent fourth double arch was soon demolished because it was unsafe.
The bridge allowed the Anio Vetus to cross the Rio Secco gorge and thus avoid several valleys along the route. It was first built in brick, resting on pillars inopus quadratum from the Augustan age, later reinforced with thickopus reticulatum supports which greatly reduced the width of the span. Erosion at the base has now revealed the oldest structures again. The name of the bridge derives from the unit of measurement in force in thePapal States (the Taulella = 72 square rods)
The bridge crossed the gorge of Caipoli, with two parallel arches, one for the aqueduct and another for the service viaduct. The abutments of the bridge are made ofopus quadratum (45 cm [18 in] blocks on each side) reinforced in the Augustan era withopus reticulatum walls.
The downstream channel was blocked causing the water to fall into the gorge in which a dam held the water to create a settling tank and another conduit then transported the water to a tower via a siphon, and into a new channel (by-passing the dilapidated Inverso bridge). From the resultant lake, water was used for a nearby system (perhaps anymphaeum or thermal baths). However this created instability over time which slowly led to the collapse of the bridge. The northern bridge abutment rested on a large block oftravertine, which in turn rested on atuff bank. The water apparently acted as a lubricant between these structures and, probably in conjunction with a flash flood or earthquake, the travertine block slid downstream, causing the bridge to collapse. The resultant flood then caused the collapse of the dam and the failure of this stretch of aqueduct.[11]
At the bottom of the gorge are two rooms dug out of the tuff bank which were most likely used to house workers during aqueduct construction and completely submerged when the dam was built.
{{cite book}}: CS1 maint: location (link) Media related toAqua Anio Vetus (Rome) at Wikimedia Commons
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