There is almost nothing to see at this site in Ardree, County Kildare, at least not with the naked eye at ground level. What exists here is more of an absence than a presence: a circular mark in the earth, roughly twenty metres across, that reveals itself only from the air and only under the right conditions, when a long dry spell causes the grass or crops above an ancient buried ditch to grow differently from everything around it.

The feature was identified through aerial photography, specifically a photograph catalogued as CUCAP BOC 70, taken as part of the Cambridge University Collection of Aerial Photography, which has contributed significantly to archaeological mapping across Ireland and Britain. What the image shows is a cropmark, the faint trace left by a fosse, which is a type of enclosing ditch, forming a ring around a small central area. The site is tentatively classified as either a ringbarrow or a ringditch. A ringbarrow is a funerary monument of prehistoric origin, typically consisting of a low central mound surrounded by a circular ditch and sometimes an outer bank, while a ringditch is a closely related form that may represent a ploughed-out or otherwise reduced barrow where the central mound has long since disappeared. The distinction between the two can be difficult to resolve without excavation.