What marks its presence is a single roof lintel, a stone laid flat across what was once the ceiling of an underground passage, now the only visible evidence that something deliberately constructed lies beneath. A souterrain is a stone-lined subterranean tunnel or chamber, typically built during the early medieval period in Ireland, and used variously for storage, refuge, or concealment. This one gives almost nothing away.

The souterrain sits within the interior of a cashel, a type of dry-stone ringfort, located just five metres to the west of the cashel's centre. Based on the orientation of that protruding lintel, the passage appears to run on a north-north-west to south-south-east axis. Beyond that, the structure is inaccessible, its full extent and condition unknown. The pairing of cashel and souterrain is not unusual in early medieval Ireland, where such underground features were often integral to the design of a defended farmstead, but the particular relationship between this passage and the enclosure above it remains unexcavated and largely unread.