In the townland of Ballyellane in County Cork, there is a ringfort that you cannot see. The field where it once stood is ordinary pasture on a south-facing slope, and nothing on the ground would suggest that anything ever stood there. A ringfort, sometimes called a rath or lios, was a circular enclosure defined by an earthen bank and ditch, used as a farmstead during the early medieval period. Thousands were built across Ireland, and thousands have since been ploughed, grazed, or built over into invisibility.

What makes the Ballyellane site worth pausing over is the contrast between what was once recorded and what now remains. The Ordnance Survey's six-inch map of 1842 shows a hachured circular enclosure at this location, meaning the surveyors noted it clearly enough to mark and represent its shape. By the time Patrick Power wrote about the area in 1923, citing 'one small lios' in the townland with a bank 'about 6ft high', the feature was still physically present and measurable. At some point between that observation and the late twentieth century, the earthwork was levelled entirely, leaving no surface trace. The 1842 map and Power's description are now the only records of what stood there.