There is a circle roughly forty-five metres across at Ballindysert in County Waterford that cannot be seen by anyone standing in it. The ground gives nothing away; the enclosure has been absorbed into farmland so thoroughly that it exists, in any practical sense, only on paper.

The earliest record of it appears as a faint marking on the 1840 edition of the Ordnance Survey six-inch map, the great cartographic undertaking that, across Ireland in the 1830s and 1840s, captured field boundaries, ruins, and earthworks that even then were fading from the landscape. At Ballindysert, surveyors noted a circular enclosure at the eastern edge of a broad plateau, a form consistent with a ringfort, the type of enclosed farmstead that was built in Ireland from the early medieval period onward. Ringforts, whether defined by a bank and ditch or simply by a raised interior, were once the most common archaeological monument in the country, numbering in the tens of thousands. This one, if that is indeed what it is, had already been reduced to a cartographic ghost by the time the Ordnance Survey reached it.

The site now sits under tillage, and the plateau setting that might once have made the enclosure conspicuous in the landscape no longer helps a visitor locate any trace of it. It is the kind of place that rewards a close reading of a nineteenth-century map more than any amount of walking the ground.