Somewhere beneath a flat, unremarkable field in Coolsickin, County Kildare, lies the ghost of a circular enclosure that only an aircraft could find. The site exists, for all practical purposes, as a cropmark, a phenomenon in which buried ditches or banks affect the growth of crops or grass above them, causing subtle differences in colour or height that are invisible from the ground but legible from the air. No earthwork survives, no mound interrupts the pasture, and when the field was visited in 1986, there was nothing to suggest that anything lay underfoot.

The evidence for the enclosure comes from a single aerial photograph, reference GSI N 414-5, which captured the circular outline as a cropmark over what is described as open, level, well-drained, improved pasture. That combination of flat terrain and good drainage is precisely the kind of landscape where ancient enclosures were often established, and where, over centuries of agricultural improvement, they tend to disappear entirely from the surface. Circular enclosures of this kind are frequently associated with early medieval ringforts, which were used as enclosed farmsteads across Ireland from roughly the fifth to the twelfth centuries, though without excavation it is not possible to say with any certainty what this particular feature represents or when it was built. The landscape of north Kildare is dense with such sites, many of them reduced to traces detectable only under particular conditions of light, soil moisture, and crop stress.