What lies there is a souterrain, an underground stone-lined passage built in early medieval Ireland, typically associated with raths and used for storage, refuge, or both. This one is partially collapsed, its full extent now readable more through surface depressions in the soil than through any intact tunnel, and what remains is just enough to suggest how ambitious the original structure was.

The souterrain sits in the south-west quadrant of a rath, a circular earthen enclosure of the kind common across Ireland from roughly the early centuries AD through to the Norman period. The underground complex appears to have been T-shaped in plan, consisting of two passages connected by a drop-hole creep, a narrow constriction between passages requiring a person to drop down through an opening, a design feature that would have slowed any intruder considerably. The first passage runs north to south, measuring roughly four metres in accessible length, just under a metre wide and about the same in height. Entry is now possible through a breach near its northern end, though beyond that point the passage is choked with rubble. A linear depression nine metres long suggests the passage continued considerably further south of the access point. A second passage, apparently running east from the northern end of the first, was reached through another drop-hole creep, now blocked. Surface depressions in the ground above indicate that this eastern arm has largely given way. The overall length of the system, accounting for what has collapsed, exceeded thirteen metres.