More precisely, a souterrain, one of those dry-stone underground passages that early medieval farming communities built beneath their settlements, likely for storage, refuge, or both. The rumour of it has persisted long enough to be noted alongside the earthwork itself, even though the passage remains unconfirmed above ground. That combination of visible structure and half-remembered underground feature gives the site an atmospheric doubling: the world you can see, and the one you cannot.

The enclosure is a rath, the Irish term for a ringfort, the most common archaeological monument type in the country. Built predominantly during the early medieval period, roughly the fifth to twelfth centuries, raths served as enclosed farmsteads for a single family or household. This one sits on a ridge in County Mayo, close to the break of slope on the south-eastern side, and commands good views over the surrounding terrain, a position that would have made practical sense for anyone keeping watch over livestock or approaching visitors. The earthen bank defining the oval, which measures roughly 34 metres east to west and 28 metres north to south, survives to an external height of around 1.4 metres on the northern side. On the north-eastern to south-south-western arc it has been reduced to a scarp, its steep face reinforced by the natural slope of the ridge. A slumped gap about 3.7 metres wide in this scarp at the north-east may mark the site's original entrance. The farm field boundaries that now cross the landscape have incorporated parts of the monument into their own logic: a straight east-west field fence overlies the bank along part of the southern arc, and on the south-west to north-west the bank itself has been pressed into service as a field boundary.

The interior is level and grassy, with a single hawthorn tree growing at its centre and a dense ring of hawthorn and hazel along the perimeter. Hawthorn has long been associated with fairy forts in Irish folk belief, and its presence here, both solitary and encircling, gives the site the quietly layered quality that many raths carry: practical origins, accumulated tradition, and a canopy that discourages casual disturbance.