What survives is a roughly 24 metres across enclosure defined by a low earthen bank, the kind of feature that can easily be mistaken for a natural undulation until you walk its perimeter and notice the deliberate curve of it.

This is a ringfort, the most common type of early medieval settlement monument in Ireland, typically dating from roughly the fifth to the twelfth centuries. Ringforts were enclosed farmsteads, the bank and its accompanying fosse, or external ditch, serving as a boundary that defined domestic and agricultural space and offered a degree of protection for livestock. At Monkstown, a field drain has done considerable damage along the western to northern arc, levelling the bank across that stretch almost entirely. The northeastern section is more forthcoming: traces of a shallow fosse remain visible there, giving a sense of how the enclosure would originally have presented itself. The survival of even that partial ditch is useful, since the relationship between bank and fosse is often what allows a feature to be identified with confidence from the ground.