Extract from Cadw Schedule description CN366
Burial cairn, probably Bronze Age, on the ridge above Cwm Lloer. Stone built circular cairn, measuring c. 20m in diameter and up to 3.5m in height. It has been disturbed in the past, with several drystone shelters constructed and a modern walker's cairn crowning the summit.
F.F. 10/02/2004

From National Trust Inventory to Carneddau Estate:
A truly massive pile of stones, the remains of what is thought to be a cairn of prehistoric date. Its centre has been extensively disturbed and both hollowed out and built into a shelter, with a further cruder shelter constructed to the NE but still within the limits of the original cairn. Between the two shelters stones have been heaped up to form a small marker cairn. There is no good indication of any kerb to the overall structure but the plan is of a roughly circular cairn of piled stones set on what was probably already a fairly prominent outcrop. Diameter 26m 30m and about 3m 4m high. The larger of the shelters within is 5m x 4m. 960m above O.D.

John Latham RCAHMW 11 December 2012