Some archaeological sites are defined by what survives. This one is partly defined by what could not be confirmed. On an east-facing slope at the southern end of a north-south ridge in Castletown, County Waterford, a large boulder sits on the inner edge of the bank of a nearby embanked enclosure. It has been listed as a possible standing stone, the kind of upright prehistoric marker that appears across Ireland as a solitary monument or in association with ceremonial landscapes. The uncertainty, though, is baked in: when investigators visited in 1989, the boulder was not recorded at all.

The enclosure it sits beside is itself of considerable interest. Tom Condit and Myles Gibbons, writing in the local journal Decies in 1988, identified it as a henge-type monument, a category of ceremonial enclosure typically dating to the late Neolithic or early Bronze Age, characterised by a bank with an internal ditch rather than an external one. The association of a possible standing stone with such a monument would not be unusual; across Ireland and Britain, standing stones are often found in proximity to henge monuments and other ritual enclosures, forming part of a broader ceremonial arrangement in the landscape. Whether the Castletown boulder was ever deliberately raised, or whether it is simply a large stone that found its way into the archaeological record through ambiguity, remains an open question.