At Knockanacullin in County Waterford, there is a ringfort that has managed to disappear almost entirely from the landscape, while leaving enough of a trace in the historical record to confirm it was once genuinely there. Ringforts, which were enclosed farmsteads typically built during the early medieval period, usually survive as raised circular earthworks, sometimes with a bank and ditch still legible in the grass. This one is different: situated on flat pasture, it is not visible at ground level.

What makes its history quietly interesting is the way the site appears to have changed shape between two surveys. The Ordnance Survey six-inch map of 1840 records it as an oval embanked enclosure, roughly 40 metres north to south and 30 metres east to west. By the time the 1928 edition was surveyed, the same feature was recorded as a D-shaped enclosure, with its northern edge truncated by an east-west field bank. The dimensions had shifted too, to approximately 40 metres east to west and 25 metres north to south. Whether the shape changed in the ground between those dates, or whether the two surveyors simply interpreted a degraded earthwork differently, is impossible to say now. Either way, the field bank that cuts across the northern arc tells its own quiet story about agricultural activity gradually overwriting what came before. By the time anyone looked closely again, the enclosure had been absorbed into the surrounding pasture so thoroughly that nothing remains to see from a standing position.