TheAltar Stone is a recumbent centralmegalith atStonehenge inEngland, dating to Stonehenge phase 3i, around 2600 BCE. It is identified as Stone 80 in scholarly articles.
Its name probably comes from a 1620 comment byInigo Jones who wrote:
‘... whether it might be an Altar or no I leave to the judgment of others’.[2]
Map of Stonehenge monument and numbered plan of individual stones. The Altar Stone (in green) is located near the center of the monument.
The Altar Stone is made of a purplish-green micaceoussandstone and was thought to have originated from outcrops of theSenni Beds formation of theOld Red Sandstone inWales, though this has not been fully established.[3][4] Research published in 2024 claims to show that "the Altar Stone’s age fingerprint identifies it as coming from theOrcadian Basin in north-eastScotland".[5][6]
Stone 55 (asarsen megalith) lies on top of Stone 80 (Altar Stone) perpendicularly, and is thought to have fallen across it. The Altar Stone weighs approximately six tons and (if it ever was upright) would have stood nearly two metres tall. Some believe that it always was recumbent.[7] It is sometimes classed as abluestone, because it does not have a local provenance.
Stone 80 was most recently excavated in the 1950s, but no written records of the excavation survive, and there are no samples available for examination that are established as having come from the monolith.
