These underground stone-lined passages, typically constructed during the early medieval period, were built for purposes still debated among archaeologists, variously proposed as refuges, storage spaces, or secure enclosures attached to the ringforts above them. At Kilbarry, the structure remained entirely unknown until the earth above it gave way.

In April 1989, machinery passing over the ground caused a collapse, and the souterrain beneath was revealed for the first time in what may have been centuries. It sits within a ringfort, the circular earthen enclosure that was the standard unit of rural settlement in early medieval Ireland, and the two features together represent a familiar pairing in the Irish archaeological record. The collapse that disclosed the souterrain also sealed it: the entrance became blocked with fallen earth, leaving the interior inaccessible. No excavation or clearance appears to have followed, and the passage remains unexamined below ground.