It exists, for now, only as a cropmark, the kind of faint biological signal that reveals itself not to a person standing in a field but to a camera mounted in a passing aircraft. When crops grow over a buried ditch, or fosse, the soil above it retains moisture differently, and the plants above it respond in kind, growing taller or a slightly different shade. From the ground, nothing. From the air, a circle.

The enclosure at Ballyda came to light on an aerial photograph taken on 9 July 1969, as part of a Cambridge University Collection of Aerial Photography survey. The image shows a roughly circular feature approximately twenty metres in diameter, its outline traced by the ghost of a fosse, a ditch that once enclosed something, though what exactly remains unknown. Enclosures of this kind in Ireland are associated with a wide range of functions and periods, from early medieval ringforts used as farmsteads to prehistoric ceremonial sites, and without excavation the Ballyda example cannot be pinned to any particular era or purpose. In the decades since that photograph was taken, the surrounding land has been subdivided, and the enclosure now falls within the north-eastern corner of a smaller field than the one captured in 1969.

There is little a visitor could practically do with this one. The enclosure is invisible at ground level, and its precise location within a working agricultural field makes access unlikely. It is the kind of site that matters more for what it implies than for what can be seen: that the landscape of Kilkenny, like most of rural Ireland, carries within it a great deal that farming, subdivision, and the passage of time have not yet erased, even if what remains is legible only to the aerial eye.