By 1907, when the Ordnance Survey recorded it on their six-inch series, the D-shaped ringfort at Lisaginny was a small feature on the landscape, and in the century since it has lost even more of itself to the creep of field boundaries and agricultural reworking. What survives is the southern portion only, an overgrown D-shaped area roughly eighteen metres east to west and twelve metres north to south, defined by a scarp that still stands about a metre above ground level at its south-south-east edge. North of a field bank that cuts across the site east to west, the monument has no visible profile at all.

Ringforts, known in Irish as raths when they rely on earthen banks rather than stone, were the most common form of enclosed farmstead in early medieval Ireland, typically dating from roughly the fifth to the twelfth centuries. They served as protected homesteads for farming families, and many thousands survive in varying degrees of completeness across the country. The Lisaginny example is modest by any measure, and it lacks both a visible fosse, the external ditch that often reinforces a rath's bank, and any identifiable entrance gap. What makes it quietly notable is the presence of a souterrain in its interior. A souterrain is a stone-lined underground passage or chamber, often associated with ringforts, and thought to have served variously for storage, refuge, or drainage. The one at Lisaginny sits within what little remains of the enclosure, a subterranean feature outlasting the earthworks that once surrounded it above ground.