At Kilhile in County Wexford, a ringfort survives not as an earthwork you could stumble across on a walk, but as a cropmark, a ghostly outline pressed into the soil that only becomes apparent when viewed from above. These cropmarks appear when buried features such as ditches or banks affect the moisture and nutrient content of the soil above them, causing the vegetation growing over them to ripen or wither at a slightly different rate than the surrounding ground. The result, seen from an aircraft in the right season and light, is a faint but legible silhouette of something long gone at surface level.

What the aerial photographs reveal is a subcircular enclosure roughly thirty metres in diameter, defined by a single fosse, which is the term for a ditch dug to demarcate and defend a settlement. This kind of enclosed farmstead, known as a rath or ringfort, was the standard form of rural habitation in early medieval Ireland, broadly from the fifth to the twelfth centuries. Thousands survive across the country in varying states of preservation; many others, like this one at Kilhile, have been ploughed flat over the centuries, leaving only the buried negative of their original ditches. The Kilhile example sits towards the bottom of a west-facing slope, a positioning that would have offered its original occupants reasonable shelter and likely access to lower, wetter ground nearby. Its presence was captured on aerial photography held in the Cambridge University Collection of Aerial Photography, and confirmed again on photographs taken in 2000.