In a field in Grangerosnolvan, County Kildare, there is nothing to see. That, in a sense, is the point. What lies here is visible only from the air, and only under the right conditions, when differential crop growth betrays what lies beneath the soil: the ghostly outlines of an ancient enclosure and the remnants of a small field system that have otherwise vanished entirely from the surface of the land.

Aerial photography has revealed cropmarks, the faint discolouration in growing crops caused by buried ditches and banks affecting moisture and nutrients in the soil above them, that trace the fosses, or boundary ditches, of a roughly circular enclosure estimated at around 45 metres in diameter. Extending to the south-east of this central area are several small sub-rectangular fields, suggesting that whatever settlement or activity the enclosure once contained was supported by organised agricultural land nearby. Circular enclosures of this kind are a common feature of the Irish landscape and are often associated with early medieval settlement, though without excavation it is impossible to say with confidence when this particular example was in use or what purpose it served. The very absence of surface evidence makes it typical of a broader category of sites that survive only because the crop remembers what the ground no longer shows.