At roughly 32 metres east to west and just over 30 metres north to south, it is a fairly typical rath in scale, though the survival of two distinct banks with a fosse, or defensive ditch, between them marks it out as a more elaborately constructed enclosure than many of its kind. Raths are the remains of enclosed farmsteads built predominantly during the early medieval period, roughly 500 to 1000 AD, and thousands of them survive across Ireland in varying states of preservation. This one is described as being in fair condition, with the fosse and outer bank still legible along the northern to eastern arc of the monument.

What makes the site a little more layered is a local tradition associating it with a souterrain within the interior. Souterrains, which are stone-lined underground passages or chambers, were commonly built in association with raths and are thought to have served as storage spaces or places of refuge. The Derreen example is catalogued separately, suggesting that the underground feature has at least been noted and recorded, even if its extent or condition has not been fully described here. Two gaps in the enclosure, one to the west at six metres wide and one to the east at 7.2 metres, may represent original entranceways, though later disturbance cannot be ruled out. A field wall cuts across the monument at both north and south, a familiar situation across rural Ireland where centuries of agricultural use have left their mark on older earthworks.