In a cultivated field on a gentle south-facing slope in Boley Little, County Kildare, there is an enclosure that nobody walking the land today would ever know was there. It leaves no ridge, no hollow, no trace whatsoever at ground level, yet it was once clearly visible from the air, its outline betrayed by the differential growth of crops over buried ditches.

A 1968 aerial photograph, taken as part of the Cambridge University Collection of Aerial Photography, captured the site as a cropmark, the kind of ghostly impression that appears when buried features affect soil moisture and cause crops above them to grow at slightly different rates or to ripen unevenly. What the photograph revealed was the cropmark of a fosse, a defensive or boundary ditch, enclosing a roughly rectangular area estimated at around 40 metres north to south and 35 metres east to west. Attached to the northern side was what appeared to be a possible triangular enclosure, also around 40 metres along its longest axis. The shapes and their relationship to one another are unusual; rectangular enclosures of this kind are known from the Irish archaeological record, but the addition of a triangular element is a less common configuration. The whole complex has since been levelled by agriculture, and a second enclosure of similar character lies approximately 20 metres to the south, that one likewise lost to the plough.