No trace of it shows at the surface, no lintel protrudes from a ditch, no hollow ground betrays a collapse. What survives instead is local memory, the kind that tends to attach itself to souterrains, the stone-lined underground passages built during the early medieval period in Ireland, typically associated with ringforts and used variously for storage, refuge, or ventilation of adjoining structures. The tradition of a tunnel running under the road is, in its own quiet way, as interesting as any excavated chamber: it suggests that something was once known, seen, or disturbed, and that the knowledge was passed on even after the physical evidence disappeared.

Souterrains were constructed across Ireland from roughly the seventh to the twelfth centuries, and County Cork has a considerable concentration of them. They were built using a corbelling or lintelling technique, with upright stone slabs and flat capstones forming a narrow underground gallery, often with chambers branching off a central passage. Many have been lost through road-building, field drainage, and agricultural improvement, their stones reused or their roofs simply crushed under the weight of centuries. At Ballymichael, the probability is that exactly this kind of disturbance occurred, with road construction the most likely culprit, leaving only the oral tradition of a tunnel as the residue of whatever once lay there.