The enclosure is oval rather than perfectly circular, measuring roughly 39 metres north to south and 43 metres east to west, and it sits on a slight natural rise in gently undulating grassland, with a high hill visible to the north. Earthen banks and an external fosse, the term for a defensive or boundary ditch dug around the perimeter of a ringfort, once defined the whole circuit. Sections of the bank have been quarried away at three points, and part of the fosse has been filled in on the southern side, most likely as farmland was extended and reorganised across the centuries.

The interior tells its own quiet story. The ground slopes from north-west to south-east, and faint traces of wide cultivation ridges run in the same direction, suggesting the enclosed space was turned over to tillage at some point after the ringfort ceased to function as a settlement or enclosure. Ringforts, known in Irish as raths when defined by earthworks rather than stone, were built in their thousands across Ireland, mostly during the early medieval period, and served as enclosed farmsteads for families of varying social rank. The Monroe example sits in a notably dense stretch of prehistoric and early historic activity: a ring-barrow and a stepped-barrow lie around 130 metres to the north-north-west, and a second ringfort stands roughly 200 metres to the north-north-east. Field fences, added at some later point, now cut across the western interior, intersect the perimeter at the north-east, and curve around the outer fosse from north-west to north-east, binding the ancient boundary into the modern field pattern as though the two were always part of the same design.