A souterrain, which is an underground stone-built chamber or tunnel typically associated with early medieval settlement, lies inside a concentric enclosure, its entrance sealed under a heap of stones. No trace of it is visible from the surface today.

The record of its existence comes from Athy, writing in 1913 to 1914, who noted the blocked entrance within the interior of the enclosure. Concentric enclosures, which feature two or more roughly circular earthen or stone boundaries arranged around a central area, are associated with early medieval occupation in Ireland and often enclosed settlements of some social or ritual significance. The souterrain inside this one would originally have served some combination of purposes familiar from comparable sites, storage, refuge, or access to a water source, though nothing in what Athy recorded points to any particular use here. The entrance was already obstructed when he visited, suggesting the passage had fallen out of use long before the early twentieth century.