It is a rath, the Irish term for a ringfort, a type of enclosed homestead built in the early medieval period, typically between the sixth and tenth centuries, in which a circular or oval area was defined by one or more earthen banks and used as a farmstead or the residence of a local family of some standing. This one at Attinaskollia sits on the ridge's edge in a position that would once have commanded a clear view over the surrounding lowland, a stream-fed hollow dropping away to the north-north-west.

The rath takes a broadly oval form, measuring roughly 29.5 metres on its longer axis and about 25.9 metres across. The earthen scarp that defines it still stands to around 1.5 metres in height along the south-south-east to north-west stretch, but it has deteriorated elsewhere and a section to the east-south-west has been partially dug away. Where the natural ridge contours fall outside the western and northern edges, they form a kind of natural terrace, its outer edge defined by a scarp rising to about 1.8 metres, before it slopes off to the south-west and north. Inside, the ground is level. Near the western scarp there is a shallow depression, roughly five metres by four, which local knowledge suggests may be connected to a souterrain beneath, one of those underground stone-lined passages or chambers that early medieval communities used for storage or, occasionally, refuge. The interior has also been bisected by a later field wall running roughly north to south, with a sod-covered bank extending through the south-west quadrant, the ordinary marks of subsequent agricultural life laid over the older structure.

Gorse, brambles and blackthorn grow intermittently along the perimeter and push inward in places, which is in many ways typical of these sites across the west of Ireland. The vegetation both obscures and, in a small way, preserves what remains.