There is no surface trace of it, no marker, no depression in the grass to suggest that anything unusual lies below. It came to light only by accident, in 1975, when ground was being broken for a building, and it was examined, recorded, and then sealed again.

A souterrain is an underground stone-lined structure, typically associated with early medieval settlement in Ireland, and thought to have served as a place of refuge, storage, or concealment. The example at Inchinapallas is a particularly well-formed specimen of the type known as a beehive chamber, meaning the stones are corbelled inward to create a domed interior without mortar. Archaeologist C.J.F. McCarthy, who investigated the site shortly after its discovery, recorded a single circular chamber measuring 3.35 metres in diameter and 2.43 metres in height, with two passages extending outward from it. His account, published in 1977, remains the primary source of what is known about the interior. The site was closed not long after the investigation, returning the chamber to the dark it had occupied for centuries. A second souterrain lies approximately 20 metres away, hinting that this was once a more substantial settlement, though the pasture above gives nothing away.