This is a rath, a type of ringfort that was once among the most common features of early medieval Ireland, serving as a farmstead or high-status enclosure for a single family or small community. What survives at Ballygreighan is a raised circular area roughly 22.5 metres east to west and 20.5 metres north to south, surrounded by an earthen bank that time has treated unevenly.

The bank itself tells a quiet story of gradual erosion. On the interior face it stands only about 0.35 metres high, little more than a low step, while on the exterior it rises to around 1.5 metres at the north-east and reaches its most pronounced point at the south-west, where the external scarp climbs to approximately 2.6 metres. For much of the circuit, the bank has been worn down to little more than that scarp edge, its original mass long since slumped or removed. A gap of about four metres in the eastern side of the bank may preserve the location of the original entrance, which in ringforts of this kind was often oriented toward the east or south-east. Inside the southern portion of the enclosure, a hollow measuring roughly 5.4 metres east to west and 3.8 metres north to south, and sinking to about 0.6 metres in depth, hints at some internal feature or subsidence, though what it represents is not recorded.

The siting on the ridge top is typical of how these enclosures were positioned, commanding views of surrounding ground and signalling presence in the landscape even as the structure itself has shrunk considerably over the centuries.