The site is D-shaped rather than the round form most people associate with Irish ringforts, a rath being an enclosed farmstead, typically of early medieval date, defined by one or more earthen banks and ditches. Here the enclosing bank, about five metres wide, survives only from the north to the east, rising to around 1.5 metres above the ground outside it. Elsewhere the platform barely lifts above the surrounding pasture, giving the whole enclosure a low, half-dissolved quality, as though the landscape has been slowly absorbing it for centuries.

Inside the enclosure stand the remains of two distinct structures. The larger is a rectangular house, internally about 8.5 metres by 5.8 metres, its stone walls now overgrown and reduced to roughly 40 centimetres in height. A doorway 80 centimetres wide survives in the southeast end-wall, with two threshold slabs still in place. Immediately outside the northeast corner of this house, a short stone-faced bank and a small stone-lined oval depression sit in proximity to each other, though what either was used for is not known. A trench was dug alongside the northeast wall of the house in the 1980s, but no findings from that intervention appear to have altered the broader picture. To the south of the rectangular house, a smaller circular hut, about 4.8 metres in internal diameter, preserves the remains of a corbelled wall, a technique in which stones are laid in overlapping courses to close a roof or wall without mortar, surviving to nearly a metre in height at the northwest. From inside this hut, a curving souterrain, an underground stone-lined passage typically associated with storage or refuge, runs outward for about 4.5 metres. The passage is drystone-built, its side-walls intact to 90 centimetres, but its roofing lintels have been taken away at some point, and the interior is now filled with debris. A further opening to the east of the hut may mark an extension of the souterrain that has yet to be fully traced.

The site was documented in A. O'Sullivan and J. Sheehan's archaeological survey of the Iveragh Peninsula, published by Cork University Press in 1996, which remains the foundational record for the area. The name attached to this location, Oonagranshee or Uaigh na Grainsighe, connects the place to a tradition of named caves in the Irish-language landscape of south Kerry, though the precise meaning and origin of that name are not elaborated in the available record. What survives on the ground is fragmentary and, in places, recently disturbed, but the combination of enclosure, rectangular house, corbelled circular hut, and souterrain within a single modest platform makes this a quietly complex site, carrying several layers of use compressed into a space not much larger than a tennis court.