A souterrain is an underground stone-lined tunnel, typically constructed during the early medieval period in Ireland, and associated almost always with nearby settlement enclosures. What makes this one quietly absorbing is its modest but precise geometry: a roughly rectangular entrance facing south-east, just under a metre wide and a metre high, leading down into a passage roofed with flat lintel stones resting on walls that have partially given way over the centuries.

The souterrain sits within a rath, a circular earthen enclosure of the kind that dotted the Irish countryside from roughly the fifth century onwards, used as enclosed farmsteads by farming families of varying social rank. The underground passage itself runs in two directions from an internal junction, extending approximately 2.5 metres to the east and 4.5 metres to the west, narrowing as it goes in both directions. Souterrains like this one are thought to have served as places of refuge, cool storage for dairy produce, or both. The entrance here is currently obscured by overgrowth, which is perhaps fitting for a structure whose whole character is one of deliberate concealment.