On a gentle north-facing slope at Carriglong in County Waterford, a circular depression in the grass quietly marks the outline of an ancient enclosure. It is easy to walk past without registering what you are looking at: a slightly dished area, roughly 21 metres across, bounded by a low scarp no more than 30 centimetres high in places. The width of that scarp, around five metres, suggests there was once something more substantial here, perhaps the remnant of a bank that has spread and settled over centuries into little more than a shallow earthen rim.

The enclosure was already old enough to be recorded cartographically when the Ordnance Survey produced its first six-inch maps of Ireland in 1840, which measured it at somewhere between 25 and 30 metres in diameter. Circular enclosures of this kind are found across Ireland and can date from the prehistoric period through to the early medieval, when they were commonly used as enclosed farmsteads or ringforts, a category of monument so numerous in the Irish landscape that they were once thought to number in the tens of thousands. Whether this particular example served a domestic, agricultural, or ritual purpose is not recorded, and the site itself offers no obvious answer, only the faint geometry of its outline pressed into the hillside.