The earthwork is easy to miss: the ground lifts only a little, the bank is modest, and the surrounding countryside gives no particular drama. But the geometry, once you know what to look for, is unmistakable. A roughly circular area, measuring about 29.5 metres north to south and 27 metres east to west, is defined by an earthen bank and a shallow external fosse, the ditch dug around the outside of a ringfort to reinforce the sense of enclosure and to direct surface water away from the interior.

Ringforts, known in Irish as raths when built from earth rather than stone, were the standard settlement type in Ireland from roughly the early centuries AD through to the early medieval period. Thousands survive across the country in varying states of preservation. This one at Ballynatra is relatively understated: the bank stands only about 35 centimetres above the interior ground surface, though it rises to around 1.2 metres when measured from the outside fosse, which gives a clearer sense of how the enclosure would originally have functioned as a boundary. The north-eastern section of the bank has been levelled, and along the arc running roughly from east-northeast to southeast, the old earthwork has been absorbed into the modern field fence system, a fate common to ringforts on working farmland, where ancient boundaries and practical ones have quietly merged over centuries of agricultural use.