On a natural flat-topped hillock on the southern bank of a small stream in Castletown, County Kilkenny, that absence has a precise date: 1958, when the site was levelled during land reclamation works.

What occupied that hillock for centuries, perhaps millennia, was a large oval enclosure, roughly 116 metres along its north-east to south-west axis and around 80 metres across. Earthwork enclosures of this kind, defined by banks and ditches that ring a raised interior space, are among the more common but least understood monument types in the Irish landscape. They vary enormously in date and function, from prehistoric ceremonial sites to early medieval farmsteads. This one sat on ground with good views in all directions, a position that would have had obvious strategic or territorial value to whoever built it. It was clearly visible on both the first edition Ordnance Survey six-inch map of 1839 and the second edition of 1899, which means it survived, largely intact, into living memory. By 1987 it had been catalogued as an earthwork, and by 1996 it appeared in the Record of Monuments and Places as an enclosure site. Then the correspondence trail ends, and so does the monument. Land reclamation in 1958 erased it completely, and today there is nothing visible at ground level to suggest it was ever there.