It is in fact a rath, the commonest type of ringfort in Ireland, a form of enclosed farmstead that was built and occupied largely during the early medieval period, roughly between the fifth and twelfth centuries. Thousands survive across the country in varying states, but many have been levelled by agriculture or lost to development. This one, at Cappanagoul, has kept its shape.

The enclosure measures 43.8 metres east to west and 43.7 metres north to south, making it almost exactly circular. An earthen bank, rising about 1.1 metres on its interior face, defines the boundary, and beyond it runs an external fosse, a defensive ditch, reaching roughly a metre in depth along the arc from south round to north-north-west. The main entrance, three metres wide, faces east-south-east, which is a typical orientation for ringforts and broadly aligned with the rising sun. A narrower gap of 1.3 metres opens to the north-north-west, possibly a secondary access point or a later breach. The bank and fosse are now heavily overgrown, which has helped preserve the earthworks by slowing erosion, though it also means the structural detail is easier to feel underfoot than to see at a glance.