At Ballydoogan in County Sligo, one entry marks a place where something almost was. For several years, a site here carried the designation of a possible enclosure, the kind of circular earthwork that in Irish archaeology often signals early medieval settlement or a defined boundary of some ritual or agricultural purpose. The only problem was that no such enclosure existed.

The site entered the Sites and Monuments Record in 1989 on the strength of a circular feature spotted in a high-level aerial photograph. Aerial survey is a genuinely powerful archaeological tool, capable of revealing crop marks, soil discolouration, and subtle earthworks invisible at ground level. In this case, however, the feature turned out to be a misreading of the image. Ballydoogan never appeared on any edition of the Ordnance Survey six-inch maps, and when the ground was actually examined, no archaeological remains were found. By 1995, the site had been quietly dropped from the Record of Monuments and Places, the statutory inventory that carries legal weight in Ireland. It left no trace in the landscape because there was never anything there to leave one.