Most ringforts survive as awkward interruptions in an agricultural landscape, half-swallowed by later divisions of land. This one is different: the boundaries that once ran near the site have been removed, while a single field boundary follows the outer edge of the fosse to the south-east, as though the modern landscape quietly deferred to the older one.

A ringfort, or rath, is essentially a circular enclosure defined by one or more earthen banks and ditches, used primarily in early medieval Ireland as a farmstead or small settlement. The example at Ardnacrohy sits on a slight slope facing east-north-east, at the end of a broad east-west ridge, a position that would have offered reasonable visibility across the surrounding ground. The enclosure is roughly circular, measuring about 34.5 metres north to south and 37.2 metres east to west. Its defences are not uniform all the way round: a substantial earthen bank, rising to around 2.65 metres on its outer face, curves from the south-east to the north-north-east, while the remainder of the circuit is defined by a scarped edge, essentially a cut slope rather than a built bank. An external fosse, a ditch running to roughly 0.75 metres deep and 3.3 metres wide, reinforces the northern and eastern sides, and a further outer bank rises to 1.3 metres along the north-east to south-east arc. The entrance is a causeway gap 7.2 metres wide at the north-east. The record was compiled by Denis Power and uploaded in August 2011.

The interior slopes downward toward the north and is largely under pasture, though the north-east quadrant has been taken over by overgrowth, which makes close inspection of that section more difficult. The causeway entrance at the north-east is the clearest point of orientation and gives the best sense of how the banks and fosse were arranged to channel approach to the site. Because the surrounding field boundaries have been cleared away, the outer earthworks are more legible here than at many comparable sites, and the relationship between the scarped edge and the built bank sections is worth tracing as you move around the circuit.