No trace of it appears at the surface, yet the story persists, passed along as the kind of detail that tends to survive precisely because it feels true. The site itself is barely legible in the landscape: a low scarp, a slight thickening of the ground that hints at something deliberate, something that was once considerably more substantial.

The third edition of the Ordnance Survey six-inch map, published in 1920, recorded what was then still recognisable as a roughly circular enclosure approximately sixty metres in diameter. Enclosures of this type are among the most common, and most poorly understood, monument classes in the Irish countryside. Many are the remains of ringforts, the farmsteads of early medieval Ireland, built from earthen banks and ditches to define a domestic space and mark out a household's territory. Others are earlier still. Most of what stood at Glenrevagh has since collapsed or been absorbed into the surrounding grassland, leaving only the scarp visible from the east-south-east to south. The reported tunnel, if it exists, would most likely be a souterrain, an underground stone-lined passage associated with early medieval settlement sites, used variously for storage, refuge, or ventilation of underground chambers. That no surface trace survives makes verification difficult, and the feature remains a matter of local knowledge rather than confirmed archaeology.

The site sits quietly in open farmland with little to announce itself to a passing visitor. What remains above ground is modest enough that it could easily be walked across without recognition, which is, in its own way, part of what makes it worth knowing about.