The monument comprises the remains of a prehistoric chambered cairn, set on a hilltop overlooking Stornoway harbour.
The cairn is spread over an area 30m in diameter, largely covered by dense scrub. Three stones remain upright of a peristalith or kerb, indicating an original diameter of 24m. The tallest of these is 1.4m long. The chamber was within the SE quadrant of the cairn, and is aligned approximately NE-SW, being 5m by up to 1.25m across internally. The largest of the slabs forming the chamber walls is 2m long. No capstones survive, and the cairn is reduced so that it stands only 0.5m higher than the floor of the chamber. There is a hollow in the SW quadrant that may represent a second chamber, but this is uncertain. A mid-19th-century track clips the E edge of the cairn, and a modern cairn, built in 1902, is set on the E edge of the chambered cairn, and is formed of material robbed from the latter. This modern cairn, which originally supported a flagpole, is on the supposed location of the medieval gallows which gives the hill its name, Cnoc na Croich - Gallows Hill.
The area to be scheduled is circular, 45m in diameter, with the modern cairn lying just within the E side of the area to be scheduled, as shown in red on the accompanying map extract.