This is really for Scottish TMAers...
Well googling because of ignorance, mine, ( though they are to be found only in Scotland and Ireland?) it turned into an interesting read, they are part of a stone circle, the 'altar' from which you can see the moon, would form part of the dimensions of the s/c. So for a start, 'Old Keig' ....
'At Old Keig a recumbent stone circle situated on a slight crest on a ridge, and within a narrow windbelt. A recumbent stone, 16ft long on top, 6ft thick, 6 3/4ft high, two flankers, the westerly 5 1/4ft above the turf, the easterly 9 1/2ft, and a third orthostat, 9 1/2ft high, to the east, survive. Five other earth fast stones in the vicinity look as if they have been disturbed.'
