Roughly thirteen metres across, it is defined by the low remains of an earthen bank, an enclosure of the kind that appears across Ireland in varying states of survival, and this one has worn down to something easy to overlook: a width of about 1.8 metres and a height of just 0.3 metres, with intermittent traces completing the circuit where the bank has not survived intact.

Enclosures of this broadly circular type are among the more common, and more enigmatic, features of the Irish archaeological landscape. Depending on their form, date, and context, they can represent the remains of a ringfort, a type of enclosed farmstead used from roughly the early medieval period through to the early Norman era, or they may be earlier still, associated with prehistoric settlement or ritual activity. Without excavation, a low earthen ring like this one resists confident classification. What survives at Cloonaghlin is the outline, a faint geometry pressed into the hillside, where outcrops of bedrock still show through the turf.