|Notes:||Sitting on the summit of an islet south of Shapinsay, the prominent cairn is slightly oval in plan, measuring 19.2 by 17.5m. A modern marker cairn has been built to the north-east of its centre.|
In 1981, the cairn’s edges were said to be well-defined, rising to a maximum height of 1.8m at the north-western and south-western sides .
The chamber, orientated ESE to WNW, was defined by the tops of three pairs of transverse slabs and one stone of a fourth pair. The back-slab usually found within Orkney-Cromarty stalled chambers was not visible.
The surviving pairs varied from 0.35m to 0.6m apart, with the visible compartments along the north-eastern side measuring 1.7m, 1.6m and 1.7m long.
A filling of loose stones within the chamber and suspected entrance passage led Davidson and Henshall to conclude the chamber had been investigated .
Assuming he was referring to this cairn, Rev George Barry’s account of Helliar Holm confirms this “investigation” had taken place before 1805:
“At present, [the island] contains the ruins of an old chapel, and a Picts-house that has been opened.” 
Tombs of the Isles - Helliar Holm, Shapinsay