In a field near Prumpelstown in County Kildare, something circular lies just beneath the surface of the soil, invisible to anyone walking past but revealed, under the right conditions, from the air. A ring-ditch, the circular trench that once surrounded a prehistoric burial mound or funerary monument, leaves its trace in the earth long after the mound itself has been levelled by centuries of agriculture. When crops grow unevenly over buried features, drought stress causes the vegetation above ditches and pits to differ in colour or height from surrounding growth, producing what archaeologists call a cropmark. It is through exactly this kind of ghostly impression that the Prumpelstown ring-ditch came to be recorded.

An aerial photograph captured the cropmark of this feature, and it does not stand alone. A second ring-ditch lies close by, making this a paired monument of the kind sometimes associated with Bronze Age burial practices, where family groups or successive generations were interred in neighbouring enclosures. Ring-ditches of this type are found across Ireland's midlands and eastern counties, where low-lying, well-drained soils are particularly susceptible to the cropmark effect. The Kildare landscape, much of it under tillage for generations, has yielded a considerable number of such aerial discoveries, most of them unknown at ground level and unrecorded until aircraft and cameras made the invisible legible.