About a mile to the north-west
of the Ring of Brodgar, is the site of what appears to be another prehistoric henge - the Ring of Bookan.
This massive earthwork comprises an enclosing
ditch surrounding an oval raised platform, measuring about 44.5
metres by 38 metres.
interpretation of the Ring of Bookan is not clear, although a recurring
suggestion in the past was that it housed a Maeshowe-type
cairn. Other suggestions are that the enclosed platform once featured a series
of standing stones, or a cairn.
The dimensions of the Bookan "ring", however, hint at a connection
with the nearby Standing Stones of Stenness.
At two metres deep and 13 metres across, the Bookan
ditch is wider than the ditches found at both Brodgar
and the Standing Stones, but similar in depth to the Stenness henge. The enclosed area of the Ring of Bookan is also almost identical
to that of the Stones of Stenness.
The Bookan henge lacks two features common to
Brodgar and Stenness - an entrance causeway and outer bank. These,
however, could easily have fallen victim to ploughing and farming
over the centuries.
Within the ditch are a number of stones and a
rough mound. It has been suggested that this is the remains of a
cairn, but this remains speculation.