Somewhere beneath a ploughed field in Castleroe, Co. Kildare, lies a ringfort that has all but vanished from the surface, yet continues to hold its shape in the soil. A ringfort, or rath, is a roughly circular enclosure defined by one or more earthen banks and ditches, typically dating from the early medieval period and used as a farmstead or place of habitation. This one measured around 65 metres in diameter, but centuries of agricultural use have reduced it to nothing visible to the naked eye, and what was recorded in 1955 as a slightly raised area with an earthen bank has since disappeared entirely from the landscape.

What makes the site peculiar is not the fort itself but what was placed at its centre. According to the local historian Fitzgerald, a man named James McRoberts of Castleroe was buried there in 1768, at the very heart of the ancient enclosure. His tombstone was still present when the site was described in the mid-twentieth century, sitting within what must have been, by then, a fading earthwork. The reasons for choosing such a spot are unrecorded; burial within or beside prehistoric and early medieval earthworks was not entirely without precedent in Ireland, though it remained unusual. McRoberts may simply have wished to be interred on his own land, or there may have been a more deliberate association with the antiquity of the place. An aerial photograph taken later revealed that the story underground is considerably more complex than surface appearances ever suggested. Cropmarks, which appear when differences in soil depth and moisture cause crops to grow at slightly different rates, showed not only the outline of the plough-levelled ringfort but also the fosse, a defensive ditch, of a large oval enclosure surrounding it, along with traces of internal subdivisions within that outer enclosure. The site, in other words, had layers of activity that no amount of ground-level inspection could recover.