What makes this one quietly interesting is a detail preserved in local memory rather than in any excavation report: a modern field bank running around the outer edge of the monument is remembered in the area as a third defensive bank, a folk interpretation that has attached itself to what is, by all technical measures, simply a later agricultural boundary. The gap between what a monument is and what it has come to mean in a community's imagination is often more revealing than the earthworks themselves.

The site is a rath, the most common type of early medieval enclosure in Ireland, typically consisting of a circular area defined by one or more earthen banks and ditches, used as a farmstead or small settlement. At Lissaraw, the arrangement is concentric: an inner bank, a flat-bottomed waterlogged fosse (or ditch), an outer bank, and a further external fosse, with the main entrance placed at the north-east, approached across a narrow causeway. The inner bank is 4.3 metres wide at its base; the outer, 3.5 metres. The outer bank on the west to north-north-east side appears to have been raised or augmented at some point. The monument appears on McCrea's map of County Monaghan from 1793, and on the Ordnance Survey six-inch maps of both 1834 and 1907, giving it a clear cartographic record stretching back well over two centuries. Archaeological testing carried out around 200 metres to the north in 2000 yielded nothing directly related to the fort, and in 2012 the removal of field boundaries on the northern side of the monument led to part of the outer ditch being partially closed on the west to north-west arc.