What makes it quietly arresting is not the bank itself, though at four metres high on its eastern side it is a substantial presence, but what lies beneath the ground inside it: a drystone-built souterrain, an underground passage constructed without mortar, of the kind used in early medieval Ireland for storage, refuge, or both, that bends at an angle and disappears into the earth in a direction that has not been fully traced.

The enclosure is a univallate rath, meaning it has a single enclosing bank rather than the concentric rings seen at more elaborate sites. Its interior measures approximately 24 metres north to south and 26 metres east to west, with an overgrown external fosse, or ditch, running around the outside. The original entrance is identifiable at the south-east, where a causeway crosses the fosse and a 2.9-metre gap breaks the bank. A second gap at the west is considered a later, secondary breach. The souterrain opens near the western interior, its mouth measuring roughly two metres by less than one. A low passage, only 1.2 metres high, leads to a creepway at its north-eastern end that is now too collapsed to pass through. Beyond that point, a second passage appears to continue north-westward for around 6.7 metres; its route is visible at the surface only through a line of lintels still partially embedded in the soil, the rest of the structure lying unexcavated and inaccessible beneath the field.