|Notes:||A possible chambered cairn standing on a plateau on the eastern side of Gairsay, overlooking Russness Bay.|
In 1946, the cairn – known locally as Sweyn’s Watchtower – had a diameter of c12m and survived to a height of c1.5m. At some time previously the structure had been opened, revealing a chamber.
Based on the surviving account, however, the tiny chamber does not represent a chambered cairn:
“An unrecorded excavation has revealed the whole interior, laying bare an oblong chamber 6 ft 7 ins long and from 21 ins wide at the north to 3 ft 3 ins at the south. The sides are carefully built of drystone masonry to a height of 2 ft above the floor, while the ends are formed of single slabs. The slabs or lintels which must have formed the roof have long since disappeared.”
The unexpected architecture has been suggested to represent secondary activity in the mound, given its prominent position.