It sits inside a rath, a type of circular earthen enclosure used as a farmstead in early medieval Ireland, which crowns the rise known as Cruckavilla. Most of the souterrain, an artificially constructed underground passage or chamber typically built to provide storage or refuge, has given way; what survives intact runs only 3.5 metres east to west, though the full passage once stretched somewhere between 13 and 14 metres in total.

The surviving section is a careful piece of drystone construction. Large upright slabs form the base of the walls, above which sit five to seven courses of roughly squared blocks that incline slightly inward as they rise. A projecting corbel course near the top supports massive roof lintels, now buried under roughly 45 centimetres of soil and sod. The passage tapers as it heads east, narrowing from 1.55 metres at the base to under a metre at the top, and both ends of the intact section are partly blocked by collapsed roofing slabs. West of this preserved stretch, the rest of the passage has gone entirely, visible now only as a broad, sod-covered depression that deepens and widens as it approaches the rath's western scarp. Two large stone slabs set into a field wall at the base of the hillock's northern slope may well be roof lintels taken from the souterrain at some point, reused in the practical way that stone always has been in this part of Ireland.