The usual logic of a rath, an enclosed circular homestead typically defended by one or more earthen banks and ditches, is one of self-sufficiency and agricultural practicality. Here at Rooska, on an east-facing slope above Bantry Bay, the western side of the enclosure requires no bank at all. The cliff performs that function instead, its face running flush with what would otherwise be the outer edge of the earthwork, from the west round to the north-north-west.

The surviving bank, which reaches about 1.3 metres in height, runs from the east around to the north-north-west, enclosing a roughly circular interior measuring approximately 20 metres north to south and 24 metres east to west. There is a break in the bank to the south, most likely the original entrance. The north-east quadrant has suffered considerably from erosion, and much of the bank in that area has gone. The interior itself slopes downward towards the east, so whoever once lived here would have looked out over the bay to the north, with the ground falling away beneath them. Ringforts of this kind are generally associated with the early medieval period in Ireland, roughly the fifth to the twelfth centuries, and typically served as the enclosed farmsteads of individual family groups. The use of a natural cliff as part of the defensive circuit is an opportunistic piece of siting, reducing the labour of construction while making the enclosure considerably harder to approach from the seaward side.

The fort sits in pasture today, and the erosion that has taken the north-east section of the bank is ongoing. The cliff edge is the defining feature of the site, and it is worth approaching from the south to get a sense of how deliberately the earthwork was positioned to exploit it.