A souterrain is a stone-lined passage or chamber built underground, typically associated with early medieval settlement in Ireland, and used variously for storage, refuge, or ventilation of adjacent structures. What makes this particular example unusual is not what survives but what almost certainly does not: by the time anyone thought to record it properly, a house had already been built over the site.

The geologist G. H. Kinahan, writing between 1879 and 1888, noted that on the north side of the road there had once been a low, circular earthwork, the kind of slight raised ring that usually indicates a rath, an enclosed farmstead of the early medieval period. Sometime around 1845, an underground chamber was reportedly found within or beneath this feature. Kinahan's account is brief, and the location was captured on a fieldmap produced by the Geological Survey of Ireland, suggesting the site was considered worth marking even if no detailed excavation was carried out. That map reference is now among the few concrete traces of a discovery that was otherwise absorbed into the landscape without ceremony, the rath levelled and the ground built upon.