The entrance is barely half a metre high and not much wider, a gap that demands you crouch or crawl to pass through. What lies beyond, though, is considerably more substantial: a dry-stone corridor and then a second chamber tall enough to stand in, the whole structure sealed above by carefully laid capstones. Souterrains, as these underground stone-built passages are known, appear at early medieval sites across Ireland and are generally thought to have served as places of refuge or secure storage, though their precise uses likely varied from site to site.

This particular example sits at the centre of its associated ringfort, a circular enclosure of the kind that once served as a farmstead or settlement in early medieval Ireland. The first chamber runs northwest to southeast, measuring roughly 4.4 metres in length, less than a metre wide, and just under a metre and a half in height. Its walls are built from several courses of dry-stone masonry, and the roof is carried on six lintels that rest on projecting corbelling, where stones are stepped inward from each wall to narrow the gap before the roof slabs bridge it. A small doorway formed by two upright jambs and a single lintel leads through into the second chamber, which opens out considerably: 7.5 metres long, over three metres wide, and three metres high. This chamber runs northeast to southwest, turning away from the first at roughly a right angle to form the characteristic L-shape. The contrast in scale between the two spaces is striking, the cramped entry passage giving no indication of the relative roominess beyond.