A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement in Ireland, used variously for storage, refuge, or both. This one was built in the drystone method, meaning its walls were laid without mortar, and its entrance was blocked sometime in the 1960s. Since then, no visible trace of it remains at the surface.

What makes the site quietly interesting is the local name attached to it: Liscoolcraheen. The element "lis" in Irish placenames generally refers to a ringfort, an enclosed farmstead of the early medieval period defined by one or more earthen or stone banks. That prefix suggests the souterrain may once have sat within, or immediately beside, such an enclosure, which would be entirely typical. Souterrains and ringforts are frequently found together across Ireland, the underground structure often accessible from inside the fort. The name was recorded in the Ordnance Survey Name Books for the Knockane area, which places this piece of local knowledge in the nineteenth century at least. Whether any earthwork associated with the fort survived into recent times is not recorded.