This building is one component of a group of structures which forms a deserted rural settlement on Llain Wen (NPRN 418534).
The three-compartment structure appears to have been modified and re-used over its life. The largest, central, bay measures 8.2m (NW-SE) by 3.5m within walls 0.75m thick and 0.6m high of small boulders. There is a possible entrance gap in the south long side. This structure appears to have been platformed into rising ground and built out, perhaps to as high as 0.75m. The outer scarp of this `platform? is stone revetted and forms one side of an enclosed area, below the central bay, measuring 5m by 1.6m internally, bounded on the south and west by boulder walls 0.8m thick and 0.6m high but open to the east. Against the upper end of the central bay is a fold measuring 7.6m (NE-SW) by 2.3m, projecting at each end beyond the central bay, and bounded by walls of roughly coursed stones and slabs 0.75m thick. The north and west sides are revetment walls up to 1m high where the enclosed area is cut into rising ground. The south wall is 1.2m high though may have been added to recently.

David Leighton, RCAHMW, 6 March 2013