The identifying feature is that the largest stone (the recumbent) is always laid horizontally, with its long axis generally aligned with the perimeter of the ring between the south and southwest.
[1] The builders tended to select a site which was on a level spur of a hill with excellent views to other landmarks.
Recumbent stone circles generally enclosed a low ring cairn, though over the millennia these have often disappeared.
[2] They may have been a development from the Clava cairns found nearby in Inverness-shire and axial stone circles may have followed the design.
Whilst it has been suggested by Alexander Thom that there were two circles, if there was one it was an oval shape between 18n and 22 metres wide.