Many reconstructions and models of Stonehenge incorrectly show the Altar Stone at 90° to the main solstice axis. The 80° orientation means that its long dimension points directly to the Winter Solstice Sunrise and Summer Solstice Sunset directions.
In the first photo the eastern end of the Altar Stone is seen to the left of Stone 55b, the middle section is visible between Stone 55b and Stone 156 and the western end is out of shot to the right of Stone 156.
The eastern end:
The middle section between Stone 55b and Stone 156:
The western end beneath Stone 156:
In the first photo the eastern end of the Altar Stone is seen to the left of Stone 55b, the middle section is visible between Stone 55b and Stone 156 and the western end is out of shot to the right of Stone 156.
The eastern end:
The middle section between Stone 55b and Stone 156:
The western end beneath Stone 156:
The Altar Stone has been classed as a "bluestone" ever since H.H. Thomas's work in the 1920s, via his suggestion that the builders picked it up en route from the Preseli mountains to Stonehenge - perhaps from Milford Haven, or at least somewhere in South Wales.
More recent work started to cast doubt on that idea, culminating in August 2024 with the news that the latest analysis shows that the Altar Stone most likely originated somewhere in the Orcadian Basin of Scotland - an area that encompasses NE Scotland, the Moray Firth, Orkney and the south of Shetland.
The Open Access version of the Nature paper that announced these findings is available here.
Stone 80 is of Type: Sandstone (Fine-grained, calcite-cemented, micaceous, feldspathic)
