On the north side of Moel y Llyn are the remains of a longhut located in a short, narrow dry valley with axis aligned north-east/south-west, bounded by two rocky ridges. The building is constructed on ground falling away gently to the north-east. It is substantially built of small boulders and large stones with walls 1.2m thick but now mostly tumbled and spread, measuring overall 10m (ENE-WSW) by 5m. The rubble-strewn interior measures 7.5m by 2.6m. Roughly half way down the building is a slight `step-down? suggesting a partition reminiscent of the `longhouse? tradition. A dip in the profile of the south-east long-wall was probably the position of the entrance. Outside the upper end of the building is a narrow, rush-filled ditch, probably to carry away run-off from the building.
Immediately below the building are traces of what appear to be a small enclosure, roughly 10m square. It is defined by a broad low bank across the `valley? and a narrower bank on the south-west, but these could be natural features.

OS record SN79SW10. Shown on !: 25000 scale mapping.

David Leighton, RCAHMW, 21 June 2012