It is a corbelled structure, meaning its walls were built without mortar and curve progressively inward as they rise, the stones overlapping in successive courses until they meet overhead to form a self-supporting roof. The technique is ancient but was also used in more recent centuries for agricultural shelters and storage, which is part of what makes this particular building so elusive: it could belong to almost any period.

The structure is rectangular, measuring roughly 5.15 metres along its longer axis and 3.2 metres across, with walls about 0.6 metres thick. These walls begin to corbel inward at a height of 1.3 metres, and a doorway 0.8 metres wide opens from the west side of the north wall. The whole thing is built directly against a low, west-facing rock face, which would have provided both shelter and a ready-made back wall. What gives the site its particular interest is its relationship to the surrounding landscape. About 100 metres to the south-east there are the remains of an enclosure and an associated field system, another enclosure and field system lie roughly 300 metres to the south-west, and approximately 380 metres to the south-south-west stands a mill recorded as being of notably similar construction. The clustering of these features suggests that whoever built and used this building was part of a small, functioning agricultural community occupying this sheltered canyon, working fields, grinding grain, and living within a compact and coherent landscape.

Gleninagh Mountain sits within the Burren in north Clare, a limestone upland where the bare karst surface preserves archaeological remains with unusual clarity. The canyon setting here would have offered some protection from the prevailing Atlantic weather, and the use of local stone in a corbelled technique reflects the Burren's characteristic building tradition, where timber was scarce and good flat stone was everywhere underfoot.