That absence from the maps is itself a small puzzle, because the feature is physically present enough: a raised circular area roughly forty metres across at its interior, enclosed by an earthen bank that is notably wide, even if it no longer rises to any great height, and accompanied by the remains of a fosse, the defensive ditch that typically ran around the outside of such an enclosure.

This is a rath, one of the thousands of ringforts scattered across Ireland, most of them dating from the early medieval period between roughly the sixth and twelfth centuries. They functioned primarily as enclosed farmsteads, the bank and fosse offering a degree of protection for a household and its livestock rather than serving any large-scale military purpose. The Moneensauran example has had a difficult few centuries. The northern portion of the site was cut away during road building in the early decades of the twentieth century, a fate that befell many such monuments during a period when their age and significance were not always appreciated. A field bank running northeast to southwest further divides what remains. The northwest arc of the original enclosure is the best-preserved section, and even the original entrance, which in intact ringforts can often be identified by a gap or causeway across the fosse, is no longer recognisable here.