Yet those depressions, extending over roughly 9.6 metres, are the collapsed roof of what was once a souterrain, an artificially constructed underground chamber or tunnel used in early medieval Ireland typically for storage, refuge, or both.

The ringfort itself, into which this souterrain was built, is a common enough feature of the Irish countryside, a circular enclosure defined by earthen banks and ditches, generally associated with early Christian-period settlement. The souterrain inside it adds a layer of detail to the site. When J. Coleman examined the place in 1947, he recorded that the western section of the enclosure still held recognisable remains, and from what survived he could identify massive lintels, the large flat stones laid across the top of the passage to form its roof, along with drystone walling along the sides. By the time more recent observers came to document it, even those remnants had degraded further. The structure appears to have been earth-cut rather than fully stone-built, which would have made it more vulnerable to collapse over time, though stones do break the surface in at least one of the depressions, hinting at the construction underneath.