Somewhere on a west-facing slope near the head of a quiet valley in County Waterford, an overgrown earthwork sits in a state of partial erasure, its original purpose unresolved and its entrance long since lost to the landscape. The enclosure at Tinnalyra is roughly D-shaped, measuring about 22 metres across in both directions, and the fact that nobody can any longer identify where people once passed in or out of it lends the place a peculiar self-containment, like a sentence missing its opening word.

The enclosure is defined by an earth and stone bank, the kind of boundary feature found across Ireland in various forms, used at different periods to delimit farmsteads, ceremonial spaces, or areas of managed land. Here the bank varies considerably as it runs around the perimeter: between three and three-and-a-quarter metres wide, it rises to an external height of around 2.2 metres on the southern side, dropping away on the downslope stretches to the south-west and north-west, where it survives only as a scarp, a simple cut face in the earth rather than a raised bank. The northern arc has been cut through entirely by a road bank running east to west, which truncates the enclosure and accounts for its D-shape today. There is no fosse, the ditch that typically accompanies an earthen bank and whose soil goes into building it up; the only depression near the site is a modern field drain running outside the bank from north-east to south-west, a practical agricultural feature with no archaeological significance. What the enclosure was built to contain or exclude, and when, remains an open question.