It is the kind of discovery that reminds you how much of early medieval Ireland remains just below the surface, waiting for the wrong, or right, moment to reappear.

A souterrain is an underground stone-built structure, typically associated with early medieval settlement, thought to have been used for storage, refuge, or both. The Breahig example came to light during earth-moving operations and was subsequently recorded by the Castleisland District Archaeological Survey. It is modest in scale: a drystone-built passage running roughly north to south, approximately 3.4 metres long and 80 centimetres wide, which gives some sense of how confined the experience of using it would have been. At the southern end, the passage meets a solid rock face, and it is here that the roofing slabs have been disturbed or removed. At the northern end, a small creepway, a deliberately low connecting passage designed to slow an intruder or simply to link one chamber to another, opens up, though collapse has made any further exploration impossible. The structure was built using dry-stone construction, meaning the stones were fitted together without mortar, a technique that could survive for well over a thousand years when left undisturbed underground.