It only came to attention in 1991 when the ground above it gave way and the roof collapsed, opening a hole in a south-facing pasture slope that had shown no obvious sign of anything beneath.

The subsequent investigation, carried out by Jane O'Shaughnessy of University College Cork, revealed two interconnecting chambers built to quite different specifications, and at different depths. The first is stone-built and rectangular, roughly 3.4 metres long and 1.6 metres high, with walls that are slightly corbelled outward near the top, a technique used to distribute the weight of the lintels above. A ventilation shaft enters at floor level through the east wall. At the southern end, a narrow stone-lined creepway, barely half a metre in each dimension, connects to the second chamber below. That passage drops sharply downward because the floor of chamber two sits about 0.7 metres lower than the first. The second chamber is quite different in character: earth-cut rather than stone-built, oval in plan, and roofed with a barrel vault rather than flat lintels. The two chambers, taken together, suggest either a phased construction or a deliberate variation in technique suited to the differing ground conditions at each level. To the west of the souterrain, a shallow, fosse-like depression curves in a semi-circular arc, which may be the remnant of an enclosing earthwork, the kind of boundary that would have defined a settled farmstead or small defended enclosure. The area was also the site of an early nineteenth-century settlement, meaning the ground has been occupied, and periodically disturbed, across a considerable span of time.