On the 17th of July 1967, a camera looking down from a reconnaissance aircraft recorded a cropmark, the faint but legible trace left in growing crops when buried features below the soil cause the vegetation above to ripen or wilt at slightly different rates. That momentary difference in colour and texture, preserved on one frame of aerial film, is the entirety of the evidence for this structure's existence.

Cropmark archaeology depends on exactly this kind of lucky alignment: the right crop, dry enough weather to stress the plants, the sun at a low enough angle to throw subtle variations into relief, and a camera passing overhead on precisely that day. The photograph in question, catalogued as CUCAP ASW053, was taken as part of the Cambridge University Collection of Aerial Photography, a body of work that quietly transformed the understanding of Irish and British landscape archaeology across the mid-twentieth century. The enclosure it captured at Ballykeefe is circular, a form common to ringforts, the enclosed farmsteads that were built in their thousands across Ireland roughly between the fifth and twelfth centuries, though without excavation it is impossible to assign this particular site a date or function with any confidence. A farm lane running northeast to southwest passes immediately to the southeast of the enclosure, suggesting the feature sits close enough to an established boundary that later land use may have been quietly shaped around it, even without anyone quite knowing why.