There is nothing to see at this particular spot in County Kildare, and that, in a way, is precisely the point. On an east-facing pasture slope near Rathsillagh, the ground holds the ghostly outline of what was once a field system, two parallel fosses running through the soil, invisible to anyone walking the land today but unmistakably present when viewed from above.

The evidence for this buried landscape comes entirely from aerial photography. Photographs taken in 1971 captured the site as cropmarks, the subtle phenomenon by which buried ditches and features cause the crops or grasses above them to grow at slightly different rates, creating patterns legible only at altitude and under the right light and moisture conditions. In this case, the marks showed two parallel fosses, that is, ditches, which are thought to form part of a field system associated with a possible enclosure recorded immediately to the west of the site. The pairing of a field system with an enclosure of this kind is a pattern familiar from early medieval Irish farming landscapes, where enclosed settlement sites were often surrounded by organised agricultural land. No surface trace of any of this survives, meaning the ground underfoot gives no hint of what lies beneath.