A roughly circular area, measuring about 33 metres north to south and 35.5 metres east to west, is defined by an earthen scarp that rises to 1.7 metres in height. On the western and northern sides, a shallow fosse, essentially a ditch dug to reinforce the enclosure's boundary, runs alongside it. The interior rises gently towards its centre, a feature that would once have kept the living space well-drained and slightly elevated above the surrounding land.

This is a rath, the Irish term for a ringfort, the most common type of early medieval monument in the country. Thousands were built across Ireland, typically between the sixth and tenth centuries, serving as enclosed farmsteads for a single family and their livestock. They ranged considerably in sophistication, and this one at Lisduff preserves enough of its original form to reveal some of that complexity. The scarp is terraced on the southern side, suggesting deliberate shaping of the earthwork rather than simple piling of soil. A slight inner lip, a low raised edge along the interior face of the bank, still survives to the north-east, hinting at the care originally taken in its construction.