In a field near Prumpelstown in County Kildare, a circle roughly fifteen metres across lies invisible to anyone walking past it. There is no mound, no ditch you can step over, no stonework poking through the grass. The only reason we know it is there at all is that, from the air, crops grow differently over it, betraying in their colour and height the ghost of a fosse, a circular ditch, cut into the earth long ago and long since filled in.

Aerial photography identified this cropmark from a series of Cambridge University Committee for Aerial Photography images, which recorded the outline clearly enough to map it. The feature is interpreted as either a ringbarrow or a ringditch, two related but distinct prehistoric monument types. A ringbarrow is a burial mound defined by a surrounding ditch, while a ringditch is often the same construction reduced by millennia of ploughing until the mound itself has entirely vanished, leaving only the circular trench as a faint signal beneath the soil. At fifteen metres in diameter, this is a modest example, sitting immediately to the north-east of another recorded monument in the same townland. Whether it ever held a burial, or whether that evidence has long since been destroyed, is not something the cropmark alone can answer.