The structure is a souterrain, an underground passage or chamber typically constructed during the early medieval period in Ireland, most often associated with raths, the circular earthen ringforts that were the farmsteads of their day. This particular one was mapped as recently as 1916, marked plainly on the Ordnance Survey six-inch sheet at the centre of the western half of the rath it accompanies. Sometime after that, it was blocked up, and the only surface evidence that anything lies below is a roughly circular depression about three metres across, sitting close to the rath's western bank.

Local memory holds that the souterrain was still accessible in the mid-twentieth century, which means there are likely people alive, or recently passed, who ducked into those two chambers and came back out again. Whether they were used originally for storage, refuge, or some combination of both is the kind of question that applies to souterrains generally, and this one offers no particular answer from the surface. The rath itself is recorded separately, and the souterrain is understood to sit within its western interior. The 1916 mapping gives the site a precise documentary moment, a named feature on a printed sheet, though the knowledge of its two chambers appears to come from oral account rather than any formal investigation.