The Ring of Bookan lies about a mile to the north west of the Ring of Brodgar.
Today there is little to see other than a ditch, but this is itself quite impressive being about 13 metres wide, at least two metres deep, and enclosing an area about 40 metres in diameter.
The site has not been excavated and it is not known what kind of monument may have stood here. Popular opinion holds that there may have been a Maeshowe type tomb, or a smaller cairn or cairns, and/or a stone circle.