At roughly 35 metres in diameter, the circular earthwork here is a rath, the commonest type of early medieval Irish settlement enclosure, typically formed by a raised bank and external ditch surrounding a farmstead or small homestead. What survives at Ballymanagh is modest: a curving scarp running from north-north-east to east-north-east, faint traces of a bank continuing eastward, a further scarp sweeping south, and slight remnants of an external fosse, the shallow ditch that once reinforced the enclosure's boundary, visible at the north-east. Time, agriculture, and the soft ground have done their work, and the full circuit is no longer legible from a casual glance.

Raths of this kind were built and occupied roughly between the fifth and twelfth centuries, and they are scattered across Ireland in their thousands, though many have been levelled for farmland or have simply subsided into the landscape. What makes the Ballymanagh example quietly interesting is its setting, a genuine hillock above waterlogged ground, which would have made the site naturally defensible and visible, even if the earthwork itself is now poorly preserved. The proximity of a modern house built immediately outside the monument's south-western edge is a reminder of how continuously people have found certain patches of ground useful, one settlement form succeeding another across the centuries without any particular drama.