The circular earthwork at Caherbirrane sits on a south-facing slope in pasture, its interior having shifted seamlessly from early medieval enclosure to modern feeding area, with the livestock apparently indifferent to the transition. A silage pit abuts the bank to the west, and the south-western gap in the earthen rampart opens directly into a working farmyard, making this one of those places where the archaeological and the agricultural have become genuinely inseparable.

Ringforts, sometimes called raths, are the most common field monument in Ireland, built predominantly during the early medieval period, roughly between the fifth and twelfth centuries, as enclosed farmsteads for a single family or small community. They typically consist of a raised earthen bank, sometimes reinforced with stone, encircling a circular interior where houses and outbuildings once stood. At Caherbirrane, the surviving bank defines a near-perfect circle, 29 metres across in both directions. The interior height of the bank reaches about 1.2 metres, while a natural or cut scarp on the outer face rises to around 1.5 metres elsewhere. A shallow external fosse, a drainage or defensive ditch, runs along the north-west to north-north-east arc. There are two original-seeming breaks in the bank, one to the north-east at 1.8 metres wide and one to the south-west at 3.6 metres, the latter now serving as the farmyard entrance. Importantly, a second bank once existed here; it was still visible on an Ordnance Survey six-inch map from 1940, but has since been levelled, suggesting the site was once a bivallate rath, a slightly more substantial form of ringfort typically associated with higher-status occupants.