There is a ringfort at Ballyvoreen, in County Waterford, that cannot be seen from the ground. Stand in the pasture above the low north-south ridge where it sits, and there is nothing obvious to indicate you are anywhere near an early medieval farmstead. The enclosure exists most legibly on paper, traced as a circular form roughly 40 to 45 metres across on the Ordnance Survey's six-inch map of 1840, where cartographers recorded what the eye on the ground could no longer easily read.

Ringforts, sometimes called raths, were the typical enclosed homesteads of early medieval Ireland, generally dating from somewhere between the fifth and twelfth centuries. They were defined by one or more circular earthen banks enclosing a domestic space, and many thousands survive across the country in varying states of preservation. At Ballyvoreen, the enclosure has been reduced to the point of near-invisibility at ground level, though the 1840 mapping suggests its dimensions were once substantial enough to be clearly legible from above. That the OS surveyors recorded it at all, nearly two centuries ago, means it is preserved at least as cartographic fact, even if the earthworks themselves have largely merged back into the agricultural landscape.