The word gestures at something underground and slightly ominous, and it is not entirely wrong, but it sells the place short. What the cartographers were noting was the entrance to a souterrain, an artificially constructed underground passage or chamber that early medieval communities used for storage or refuge, set within a substantial stone ringfort whose full complexity the map did not attempt to record.

The cashel, as a stone-built ringfort is known in Irish archaeological terminology, sits in the corner of a field and commands a wide view of the surrounding countryside, which is precisely the kind of position these enclosures were designed to exploit. It is roughly circular, measuring about 65 metres across in both directions, and its enclosing stone bank is still considerable where it survives intact, reaching around 8 metres wide at the base and standing to 1.2 metres on the interior side. Along the north-western to southern arc, the bank has been absorbed into later field boundaries, a fate common to ancient monuments across Ireland as farmers made practical use of ready-built stone walls. Inside the enclosure, alongside the souterrain, there are the remains of a series of beehive huts, corbelled dry-stone structures that were once roofed without mortar by courses of overlapping stone, each ring slightly smaller than the last until a capstone could close the top. Their presence alongside the souterrain suggests a settlement of some depth and organisation, though the precise period of occupation has not been firmly established in the available record.

The site is situated in a field in Knockane, north Kerry, and its elevated position means the enclosing bank and interior features are reasonably legible from ground level, even where parts of the perimeter have merged with agricultural stonework over the centuries.