Rather than levelling the outcrop and building from scratch, they reinforced it, shaping a roughly thirteen-metre plug of living rock into the raised core of a cashel, the term used for a stone-walled ringfort of early medieval Ireland. Around that central mass runs a fosse, a defensive ditch, stretching nearly eleven metres wide in places and smoothly round-bottomed where it remains clear of collapse. Beyond the fosse rises a double-faced outer wall. The whole structure sits in a pocket of scrub, hemmed in by reclaimed pastureland, with the ground climbing sharply some sixty metres to the north-west.

The antiquarian Thomas Johnson Westropp visited and noted it in 1898, describing the arrangement as 'one of two concentric rings round a rock dome', which captures the essential strangeness of the design rather well. The cashel measures just over forty-one metres at its longest north-to-south extent, a modest but deliberate enclosure. The stone facing around the central rock plug, once standing between two and two-point-two metres high, has largely collapsed inward, tumbling into the fosse and settling into a berm, a low shelf of rubble, roughly a metre high and nearly three metres wide along much of the inner edge. The facing survives intact only between the east and south-west arc. The site was already mapped on the Ordnance Survey six-inch sheets of 1842 and again in the 1920 edition, marked with the hachured lines surveyors used to indicate earthworks and enclosures. A second cashel lies roughly seventy-five metres to the west-south-west, suggesting this was not an isolated construction but part of a broader pattern of settlement or territorial marking in the landscape.