The northern third of the enclosed space lies below the surrounding ground, while the southern two-thirds rises above it, a topographical quirk that gives the site an oddly uneven quality from within, as though the ground itself is mid-conversation with the hillside it occupies.

Ringforts, known in Irish as raths, are circular enclosures typically built during the early medieval period, roughly between the fifth and twelfth centuries, and served as farmsteads or the defended residences of local landholders. This example at Ballynagalliagh measures approximately thirty metres in diameter and is enclosed by a low, broad bank of earth and stone, roughly seven metres wide, with a fosse, or defensive ditch, running along its outer edge. That ditch is nearly five metres wide in places, though from the north-east around to the south-east it has silted up over the centuries and is barely perceptible at ground level. A two-metre gap in the bank on the north-east side, now blocked by a single boulder, is thought to mark the position of the original entrance, sealed at some point in the site's long post-occupation history.