A low mound of earth along its northern flank is the only other clue. To the untrained eye it could pass for a drainage channel or a casual dip in a field. In fact it marks a souterrain, one of the dry-stone underground galleries that early medieval Irish communities built within or beside their settlements, most likely for food storage or as places of refuge in times of threat.

The souterrain sits inside a ringfort, the circular earthwork enclosure that was the standard unit of rural settlement in Ireland from roughly the early centuries AD through to the Norman period. Writing in 1914, a commentator named Neary noted that the interior ground of this particular rath, as such enclosures are also called, had been cultivated, following the natural slope of the hillside, and that the souterrain lay within that tilled garth. The fact that the land had been worked repeatedly over the centuries goes some way towards explaining why so little remains visible. Ploughing and tillage tend to gradually compress and obscure underground features, leaving only the faintest topographic trace at the surface, which is precisely what survives here.