Known in Irish as Lismoyle or Lios Maol, a name that translates roughly as the bare or flat fort, it measures roughly 37 by 40 metres across, and its enclosing bank of earth and stone still stands nearly three metres high on the eastern side. That is a substantial presence in the landscape, and the exterior fosse, a defensive ditch ringing the outside of the bank, remains traceable around much of the circuit, shallow and flat-bottomed but still legible.

A ringfort is an enclosed farmstead of early medieval Ireland, typically dating from somewhere between the fifth and twelfth centuries, built to shelter a family and their livestock rather than to serve any military function in the modern sense. Lismoyle fits this type, being univallate, meaning it has a single enclosing bank rather than the multiple concentric rings found at more elaborate sites. What sets it apart is what survives inside. The interior floor sits higher than the surrounding ground, and within it there are the stone foundations of a roughly square structure measuring 8.6 by 8 metres, with walls approximately 1.4 metres thick, projecting from a curved raised area along the western bank. A curved stone wall, some 12 metres long and about a metre thick, extends from the northeast corner of this structure northward into the bank. Along the southern and southwestern sectors, two small semi-circular mounds, each roughly 1.8 by 1.5 metres, curve into the bank; these are interpreted as possible hut sites. The entrance, to the southeast, is about 4 metres wide. Adding further interest to the area is the fact that Lismoyle sits immediately to the southeast of a separate univallate cahir, a stone-built enclosure of a related type, making this a cluster of early settlement rather than an isolated monument.