In a field in Coolsickin, County Kildare, something briefly became visible that had been invisible for centuries, and then effectively disappeared again. In 1971, an aerial photograph captured a cropmark, the faint but legible outline of a small circular enclosure pressed into the ground below the growing crops. Cropmarks form when buried features such as ditches or walls affect how plants above them grow, often revealing themselves only under particular conditions of drought, growth stage, and angle of light. Here, the outline suggested a fosse, a defensive or boundary ditch dug around a central area, describing a circle in the flat, well-drained pastureland of the Kildare plain.

By 1986, when the site was examined at ground level, there was nothing to see. The improved pastureland had absorbed whatever slight undulation or surface evidence might once have hinted at what lay beneath. The photograph, catalogued as CUCAP BGH 71, remains the sole record of the enclosure's shape and extent. Whether it was a ringfort, a later enclosure of some kind, or something else entirely, the available evidence does not say. Circular enclosures defined by a fosse are common enough in the Irish archaeological record, most frequently associated with early medieval settlement, but without excavation this one keeps its own counsel.