This is a souterrain, an underground stone passage of the kind built throughout early medieval Ireland, most commonly as a place of refuge or cool storage, constructed by corbelling, a technique in which flat stones are laid in overlapping courses to form a roof without the need for mortar or timber. What makes this particular example quietly compelling is how much of it remains out of sight and largely unverified, known as much through local memory as through direct investigation.

The opening sits at the base of the exterior bank on the north-west side of the ringfort, a circular earthwork enclosure of the type that once served as a farmstead during the early medieval period in Ireland. The entrance is just over a metre deep at minimum, and inside the fort a corresponding depression, roughly four metres long, one and a half metres wide, and less than half a metre deep, suggests the roof of a passage has partially collapsed inward over time. Local accounts hold that the passage runs southward from the entrance and is stone corbelled throughout, though the full extent and condition of the interior have not been formally confirmed.