A souterrain is a man-made underground passage or chamber, typically built during the early medieval period in Ireland, often used for storage, refuge, or both. What makes this one peculiar is not its construction or its history, but the fact that its existence rests entirely on local memory. There is no visible trace at ground surface.

The site sits beneath a cairn, a mounded heap of stones that is itself a separate monument. Whether the souterrain was built into the cairn deliberately, inserted beneath it at a later date, or simply occupies the same ground by coincidence, is not recorded. What has been recorded is that local knowledge points to something being there. That kind of oral geographical memory, the quiet insistence of people who live near a field or a hill that something lies beneath it, has sometimes proved accurate and sometimes dissolved entirely on excavation. Here, the question remains open.