It sits quietly against an east-west field wall, barely knee-high at its tallest point, and were it not for the subtle geometry of its curve and the large boulders anchoring its base, it could pass for a natural rise in the ground. What makes it worth pausing over is not its scale but what may lie beneath it: at its centre sits a near-perfect circular depression, straight-sided, roughly two and a half metres across and just over a metre deep, which researchers believe could be the collapsed entrance or chamber of a souterrain.

A souterrain is an underground stone-lined passage, typically associated with early medieval settlement in Ireland, used variously for storage, refuge, or ventilation. The enclosure at Gort na Cille is subcircular in plan, measuring about 7.6 metres north to south and 8.2 metres east to west, with a bank of earth and gravel roughly 2.5 metres wide at its base. The whole thing survives in poor condition, which is part of what makes the central depression so striking by contrast: it is the most legible feature on a site that time has otherwise done its best to erase. The place-name Gort na Cille, meaning roughly "the field of the church" in Irish, adds a layer of ambiguity. Whether that name preserves a memory of early ecclesiastical activity in the vicinity, or is simply a local toponym that has outlasted whatever it once described, is not clear from what survives on the ground.