Ring of Brodgar

Was the Ring of Brodgar a lunar observation platform? A perfect stone circle, the Ring of Brodgar retains 27 of its original 60 stones, erected with mathematical precision some 5000 years ago. They were set six degrees apart, using a standard measure of 2.72 feet, the Megalithic yard. Around 150,000 man hours of labour were required to construct this and the nearby Stones of Stenness.
Despite the statistics, no-one knows the true significance of the stones.

If you walk between the Stones of Stenness and the Ring of Brodgar, you get the impression of following a ceremonial way, possibly a burial route. It has also been suggested the Ring and its mounds were a lunar observatory, with three positions from which the moon's movements could be studied.

A fascinating speculation, but unprovable.