It is easy to mistake for a natural rise, but the geometry gives it away: a near-perfect circle, roughly 24 metres north to south and 23 metres east to west, enclosed by an earthen bank that still stands about 0.6 metres high on the interior side. On the western edge, a shallow external fosse, or ditch, runs alongside the bank, and a gap of around two metres in the eastern bank marks what was almost certainly the original entrance. Low field fences have since grown up just outside the enclosure to both east and west, threading past it as if instinctively avoiding the older boundary.

This is a rath, the Irish term for a ringfort, the most common type of early medieval monument in Ireland. Raths were typically built between roughly the sixth and tenth centuries as enclosed farmsteads, the earthen bank and fosse serving as a boundary rather than a serious fortification, defining the household's space against livestock and neighbours alike. Thousands survive across the country in varying states of preservation, and this example at Ballynacarriga is modest in scale, its bank considerably reduced by time and agricultural pressure. What gives it a particular layer of interest is what lies inside. Beneath the ferns and briars that now choke the interior, the foundations of a rectangular structure, approximately eight metres by six, survive slightly off-centre towards the east. Whether this building belongs to the original early medieval occupation or to a later reuse of the enclosure is not recorded, but the presence of identifiable foundations within such a compact earthwork adds a quiet human dimension to what might otherwise read simply as a grassy ring on a hillside.