But the dimensions tell a different story: a roughly circular enclosure measuring just over thirty-one metres north to south and thirty-two metres east to west, ringed by an earthen bank that still rises to around two and a half metres in height. For something so thoroughly absorbed into the agricultural landscape, that bank represents a considerable feat of early medieval earth-moving.

Ringforts, known in Irish as raths when formed from earth and bank rather than stone, were the most common form of enclosed farmstead in early medieval Ireland, typically built and occupied between roughly 500 and 1000 AD. They served as defended homesteads for farming families, with the enclosing bank and its accompanying external ditch, called a fosse, providing a degree of protection for people, animals, and stored goods. At Derryclogh, the fosse survives on the southern to west-south-west arc of the enclosure, though it is now quite shallow at around 0.2 metres deep. A gap four metres wide in the western side of the bank almost certainly marks the original entrance, a feature commonly found on the western or eastern faces of such monuments across Ireland.