Ackergill Tower on the shores of Sinclair's Bay, a short distance from
Girnigoe Castle. The "History of Ackergill Tower" at
www.ackergill-tower.co.uk/
states: "In 1547, Queen Mary granted a remission to George, Earl of
Caithness, from treasonably taking and holding the castle and for
keeping
the Captain -- Alexander Keith a prisoner in nearby Castle Girnigoe.
The
Fifth Earl of Caithness took Ackergill Tower by force in the late 1600's
and held it for several years until Cromwell's troops in 1671 sent the
Earl
scurrying for safety in Orkney."