Not a metaphorical one, not a collapsed ditch misread by an optimistic surveyor, but a souterrain, one of those stone-lined underground passages that early medieval Irish communities built beneath or beside their settlements, most likely for storage, refuge, or both. The catch is that nobody has confirmed it from the surface. There is no visible trace of an entrance, no telltale depression in the turf, nothing to distinguish this particular fort from any other overgrown earthwork in the county.