On the southern edge of a disused horse-exercising track on the Curragh, a shallow circular ditch barely twenty centimetres deep marks something far older than the racehorse industry that made this plain famous. The feature is a ring-ditch, a term for the buried or near-surface remains of a circular enclosing fosse, often all that survives of a prehistoric funerary or ceremonial monument after centuries of ploughing and erosion have removed the earthwork above it. This one is modest in scale, just five metres across at its flat interior, with a surrounding ditch two metres wide, and it would be almost impossible to identify on the ground without knowing what to look for.

The monument came to light through aerial photography carried out by the Department of Defence in 1999, which remains one of the most reliable methods for detecting low-lying earthworks that have been all but flattened by agriculture. On the ground, the traces are subtle: denuded cultivation ridges press in against the fosse on its western and northern sides, suggesting the surrounding land was worked for some time, gradually wearing the feature down. A band of moss, heather, and rushes, four to five metres wide, marks the outer limit of the ditch on its northern arc, the kind of differential vegetation that sometimes signals buried disturbance to the soil beneath. What makes the site particularly notable is that it does not stand alone. It belongs to a cluster of six closely associated monuments in this part of the Little Curragh, a quieter, less manicured stretch of the plain away from the main training grounds, and the grouping suggests this area may have held some concentrated significance in prehistory, though exactly what kind remains an open question.