That is, in a sense, the whole point. Somewhere beneath a north-east-facing slope in County Cork, with a roadway running along its southern edge, lie three underground chambers that leave no trace whatsoever on the ground above them. No depression in the turf, no tell-tale hollow, no stone protruding from the hillside. The site was only discovered in 1980, and even now, knowing it is there changes nothing about how the landscape looks.

What lies beneath is a souterrain, a type of underground passage or chamber cut into the earth or built from stone, found widely across early medieval Ireland and thought to have served as places of refuge, storage, or concealment. The Coolabaun example is earth-cut rather than stone-lined, with three separate chambers, each roofed by a barrel-vaulted ceiling formed from the soil itself. Each chamber also retains evidence of how it was originally built: a construction shaft, the opening used during excavation to dig out the space, subsequently sealed with a large slab set upright on its edge. According to measurements recorded by J.P. McCarthy, each chamber runs to roughly two metres in length, one metre in width, and about a metre in height, making them tight, low spaces, enough to shelter a person but not to stand comfortably. Three such chambers in sequence, each carefully closed off after construction, suggest something deliberate and considered rather than a rough improvisation.