The enclosure is oval rather than the more commonly illustrated round form, measuring roughly 58 metres east to west and 48 metres north to south, and the earthen bank that defines it still stands to around two metres in height. A stone-faced entrance, four metres wide, opens to the east, and the inner face of the bank is reinforced with boulders, a detail that speaks to the effort invested in constructing what would once have been a defended farmstead.

Ringforts, known in Irish as raths when earthen, were the most common form of rural settlement in early medieval Ireland, typically built and occupied between roughly the fifth and twelfth centuries. They served as enclosed homesteads for farming families, the encircling bank and its accompanying ditch, or fosse, providing a degree of security for livestock and inhabitants alike. At Knockacareigh, a shallow external fosse survives to the south-west and north-west, though the western stretch has been filled in where a north-south roadway now runs close to the bank. The interior carries further traces of its agricultural past in the form of cultivation ridges running east to west, the subtle corrugations left by lazy-bed or ridge-and-furrow farming, layered over the earlier occupation of the site. The garden of a neighbouring house now extends up to the southern bank, so the ancient boundary of the rath has, in an odd way, continued its role as a dividing line between domestic space and the wider landscape.