It is a rath, the Irish term for a ringfort, the type of enclosed farmstead that was built across Ireland in enormous numbers during the early medieval period, roughly between the fifth and twelfth centuries. Thousands survive in varying states of preservation, but this one at Rahanane is a particularly honest example of slow attrition: the bank is breached in numerous places, one arc has been cut through by a later field boundary, and the interior tilts gently downhill to the south-west, giving the whole enclosure a slightly lopsided, subsiding quality.

The earthwork measures approximately 27 metres across on its north-west to south-east axis. The bank, where it survives, is around 3.65 metres wide, rising just 40 centimetres above the interior ground surface but standing 1.55 metres above the exterior, which reflects how these structures worked: the bank was typically thrown up from a quarried ditch on the outside, creating a more imposing barrier from without than the gentle internal rise might suggest. The southern arc is the best-preserved section, retaining something of its original profile, while the western side has been cut away where a north-south field boundary was later driven through it. That kind of truncation is common across Ireland, where centuries of agricultural reorganisation have treated prehistoric and early medieval boundaries as obstacles rather than monuments.