A rath, as this type of monument is known, is a roughly circular enclosure defined by an earthen bank, built during the early medieval period primarily as a farmstead boundary. This example at Kilmoyly is univallate, meaning it has a single bank rather than the two or three concentric rings found at more elaborate sites, and its proportions have survived well enough to measure.

The bank itself is approximately 4.5 metres wide and still rises to around 1.4 metres above the enclosed interior, with the external face standing somewhat higher at an average of 1.9 metres. On the north-east through to the western arc of the site, a fosse, the external ditch that once reinforced the bank with material dug from below, can still be traced. It is shallow and round-bottomed, roughly 1.8 metres wide and 0.8 metres deep, though it disappears from view around the rest of the perimeter, likely eroded or filled over the centuries. A gap of around 1.6 metres on the south-east side marks what was almost certainly the original entrance, a detail that connects the surviving earthwork directly to the daily patterns of whoever lived within it.