The site is classified as a univallate rath, meaning a roughly circular enclosure defined by a single earthen bank and ditch, of the kind built across Ireland during the early medieval period as enclosed farmsteads or places of local importance. What makes this one quietly puzzling is what lies inside: a series of mounds and depressions whose origins remain uncertain, and, tucked into the north-eastern part of the enclosure, a small lintelled cavity that may represent the entrance to a souterrain.

A souterrain is an underground passage or chamber, typically constructed from drystone walling and roofed with large flat stones, the lintels. They are found in association with raths across Ireland and are generally interpreted as places of storage, refuge, or both. The example at Arda Mór is tentative rather than confirmed; the lintelled cavity has been noted but not fully investigated. The site was documented by J. Cuppage as part of the Corca Dhuibhne archaeological survey of the Dingle Peninsula, published in 1986, which remains a foundational record of the extraordinary concentration of ancient monuments in this part of Kerry. The rath itself occupies what the survey describes as a commanding position on the ridge, overlooking the valley below, which is consistent with how many such enclosures were deliberately sited to survey the surrounding landscape.

The interior mounds and hollows add an additional layer of uncertainty. They may be the remnants of structures long since collapsed, or the result of later disturbance, or something else entirely. No definitive explanation has been attached to them, and that ambiguity is part of what makes the site worth considering. The ridge location means the enclosure would have been visible from the valley, and the valley visible from it, a relationship between settlement and landscape that is easy to overlook when a site is reduced to a reference number on a map.