Man-made underground passage in Cahernamona

Eleven and a half metres of drystone passage once cut through the west half of the Cahernamona rath, but collapse has reduced most of it to a shallow depression. Only a small chamber remains standing near the middle, its roof intact while broken lintels scatter the north end. The south half has surrendered entirely to soil, leaving faint wall traces beneath the surface. Whatever lived inside that long dark tube has mostly vanished, yet the surviving chamber still holds its shape like a paused breath.