A souterrain, in general terms, is a man-made underground passage or chamber, typically dry-stone built, associated with early medieval settlement and used variously for storage, refuge, or ventilation of adjacent structures. This one exists, as far as the record goes, as a single annotation on an old map.

The sole evidence for the site comes from an annotated Ordnance Survey six-inch map held at Damer House, a Georgian townhouse in Roscrea that serves as a repository for local historical material. The annotation was made in the course of an environmental survey carried out by John Feehan, a naturalist and writer known for his detailed work on the Irish midland landscape. Beyond that mark on the map, nothing further was recorded. No dimensions, no date of discovery, no account of how or whether it was verified. The surrounding land has been reclaimed from bog, a process that can disturb, obscure, or occasionally preserve what lies beneath, and the bogland immediately to the south presumably formed part of the same landscape that once made this a meaningful location for whoever built beneath it.

The site is not visible at ground level, which means there is nothing to observe from the surface and no particular reason a passing visitor would pause here. Its interest lies almost entirely in the gap between what was noted and what was never followed up.