Others exist almost entirely as absences, visible only from the air and only under the right conditions. The ringfort at Curragh in north County Cork belongs firmly to the second category. What survives is not a monument you can walk around and immediately read, but a cropmark, the faint signature left in growing vegetation when buried ditches and disturbed soil affect how crops or grass develop above them. Seen in an aerial photograph taken in July 1989, the outline of a circular enclosure roughly 40 metres in diameter emerges from the field below, a ghostly ring pressed into the landscape.

Ringforts, known in Irish as raths when they are earthen in construction, were the dominant settlement type in early medieval Ireland, typically dating from around the fifth to the twelfth century. They usually consisted of a circular area enclosed by one or more banks and ditches, within which a family would have kept their home and livestock. At Curragh, the internal bank has been almost entirely levelled, and the fosse, the surrounding ditch, survives mainly as that cropmark pattern. An arc of what appears to be an outer fosse was also noted along the northern side, suggesting the site may once have had more than one enclosing ditch, a feature sometimes associated with higher-status settlements. A modern field fence cuts across the enclosure slightly off-centre to the east, a reminder of how thoroughly agricultural use has reshaped the ground over the centuries. Perhaps most intriguing is that a second possible circular enclosure lies approximately 120 metres to the south-southwest, within the same field, raising the question of whether two contemporary or successive settlements once occupied this quiet stretch of north Cork farmland.