Situated on Hatterrall Hill on the eastern flanks of the Black Mountains, the Garreg Las round cairns are well-preserved, largely intact burial monuments of the Early Bronze Age. The monuments are made up of turf-covered heaps of boulders. The first cairn, cairn I is oval and measures some 10m by 8m and stands 0.5m (NPRN: 417946). The second cairn, further to the west, cairn II, is round, measuring 8m in diameter and 0.5m high, with a central robbing pit 2m in diameter. Closely associated with Hatterrall Hill Enclosure (NPRN: 306449) and Hatterrall Hill Cross Ridge Wall (NPRN: 306448).
Source: Cadw Schedule Ancient Monument Record (Ref: MM302)