It is a rath, the Irish term for a ringfort, the kind of roughly circular enclosure that served as a defended farmstead during the early medieval period, typically between the fifth and twelfth centuries. Thousands of them survive across Ireland in varying states of preservation, and this one at Carrigboy is among the more worn examples, its profile reduced by centuries of agricultural use and the slow action of weather on earthen construction.

The enclosure measures approximately 34 metres east to west and is defined by a low earthen bank that survives on the eastern, south-eastern, western, and north-western sides, rising to around a metre in external height. On the arc running from the south-south-east to the west, the bank has given way to a scarp, a sharper cut edge in the ground, standing about 1.6 metres high. Some large stones embedded in this scarp may be the remnants of original stone facing, which would have given the bank a more substantial and deliberate appearance when the site was in active use. To the north, the bank has been largely levelled, surviving only as a faint rise in the ground. A gap of roughly two metres on the south-south-eastern side is likely the original entrance. The interior slopes downward toward the south, following the natural fall of the hillside.