A souterrain is an artificial underground passage, typically dry-stone built, associated with early medieval settlement in Ireland, and this one is a particularly elaborate example. Its entrance is currently choked with collapse and rubble, with barely forty centimetres of soil separating the surface from the buried roof lintel, yet below that modest threshold lies a structure of considerable scale and craft.

The three chambers are connected by narrow constricted passages known as creeps, each fitted with a drop-hole through which a person would have had to pass deliberately and with difficulty. The first chamber, aligned roughly north-north-west to south-south-east, runs to at least seven and a half metres in length and still retains a small recess cut into the western side-wall near its northern end, a feature whose original purpose is unclear but which appears in other Irish souterrains and may have served for storage or concealment. The second chamber, at just over eight metres long, is built from massive boulders with a corbelled upper course supporting the roof lintels, its northern wall curving inward in a way that suggests careful deliberate shaping rather than expedient construction. The third and largest chamber, at over ten and a half metres, follows similar methods, and notably its floor is thought to be original. References to the site appear in Holt's 1910 work and again in McCaffrey's 1952 survey, suggesting it has drawn archaeological attention for well over a century. The souterrain sits within the north-eastern quadrant of a cashel, which is a stone-walled enclosure associated with early medieval settlement, a pairing that was common in early medieval Ireland, where souterrains often served enclosed farmsteads as places of refuge or cool storage.