One of a group of buildings located on a rocky shelf above Cwm Twrch. This building of two compartments is of markedly different character to its neighbours. Overall the building measures 18m long (NW-SE) by 5m wide. The north bay is of dry-stone and boulder construction with several courses surviving to 1.4m high at the north-west end. Some boulders on the west side may have been standing naturally when the building was constructed. Internally it measures 7.8m (NW-SE) by 2.5m. There is the vague suggestion of a cross-wall at the north-west end. Flat slabs within the interior suggest the floor may have been paved. There is an entrance in the south-east corner.
The south compartment abuts the north one on a slightly different alignment. It measures 8m (NW-SE) by 5.2m overall and is defined by boulder-faced walls 0.9m thick but much lower than in the north bay, being no more than 0.3m high. There is a cross wall 3.5m from the south-east end but no obvious entrances. This end of the building is constructed of boulders forming a platform over 1m high, thus levelling the interior.
Immediately south-west of this compartment are the poorly defined footings of a rectangular building measuring overall 8.8m (N-S) by 4m. The slab-faced walls are 0.9m thick. A line of small boulders runs from the north-west corner and connects with crudely constructed dry-stone shelter built against rock outcrop. It is roughly square on plan and measures 4.5m across with an entrance in the south-east corner.

David Leighton, RCAHMW, 8 January 2001