Early Ordnance Survey maps marked both a circular enclosure and a feature labelled simply 'Cave' at this location; by the time the second edition was printed, the enclosure had already vanished from the landscape and was recorded only as a site of something that had been. What remained, and still remains, is more interesting than a grassy bank.

On the north-western face of the flat-topped hillock, a narrow opening measuring roughly 0.6 metres by 0.75 metres leads into a souterrain, an underground passage of the kind commonly associated with early medieval ringforts in Ireland, typically used for storage, refuge, or both. This one is drystone-built, its roof formed from flat lintels laid horizontally across the passage walls, and it runs on an east-west alignment. The western end appears to have collapsed at some point. Local tradition holds that a second entrance once existed on the south-eastern side of the hillock, now closed up, which would suggest a second passage running at right angles to the first. If that is the case, the underground element of this site is considerably more elaborate than its modest opening implies.

The hillock sits in pasture a short distance west of Derriana Lough. The souterrain opening on the north-western face is small enough that it could easily be missed on a casual walk across the ground, and the collapsed western passage means exploration is limited. What is visible, though, is the entrance itself: a precise, carefully constructed gap in the hillside that has outlasted every trace of the structure it once served.