The removal of a lintel during agricultural work exposed an underground chamber that had sat undisturbed beneath a field for centuries, its existence entirely unknown until that moment of accidental excavation. The discovery is a reminder of how much early medieval Ireland lies just below the surface of ordinary farmland.

A souterrain is a man-made underground structure, typically stone-lined, associated with early medieval settlement and used variously for storage, refuge, or both. This one sits on the line of the bank of a rath, the circular earthwork enclosure it would originally have served, and lies roughly a hundred metres from a tidal inlet of the River Nore and Barrow. The chamber is oval in plan, measuring 3.2 metres along its northeast to southwest axis and between 1.2 and 1.9 metres across. Its long walls are built using corbelling, a technique in which successive courses of stone project slightly inward over one another until they meet a line of capstones, or lintels, running along the length of the roof. The southwest end of the chamber has since collapsed, but the northeast end survives to a height of 1.3 metres and contains what is now the entrance point. A second lintelled entrance, also at the northeast end, is blocked and measures just half a metre wide with a visible height of 0.4 metres, suggesting the original access was deliberately tight, whether for structural reasons or to restrict passage.