That is, in a sense, the point. Somewhere beneath the north-eastern corner of a ringfort in mid Cork, a souterrain, an underground passage or series of chambers typically cut from earth or stone and associated with early medieval settlement, lies completely backfilled and invisible at the surface. No hollow in the ground, no depression in the grass, no hint that anything is there at all.

When the archaeologists M. J. O'Kelly and E. Fahy of University College Cork came to inspect the site, the souterrain had already been filled in before they could examine it. What they had to work with was local testimony rather than direct observation. That testimony described four rectangular, earth-cut chambers, a relatively substantial arrangement that would have provided storage, shelter, or refuge for the inhabitants of the ringfort above. A single object survived to give the site some tangible character: a grindstone, twenty-four centimetres in diameter and eight centimetres thick, recovered from within the souterrain and recorded by McCarthy in 1977. It is a modest object, the kind used for sharpening tools or processing grain, but it places ordinary domestic life inside those vanished chambers in a way that formal description cannot quite manage. Someone brought it underground, or left it there, and it outlasted everything else about the place.