Not obscured by undergrowth, not ruined down to a single course of stone, simply gone from the surface of the ground entirely, leaving no physical trace that anything was ever there. The only evidence that it existed at all comes from maps and aerial photographs taken decades apart.

A rath, as this type of monument is known, is an early medieval farmstead enclosed by one or more earthen banks and ditches, once home to a farming family of some local standing. Thousands of them survive across Ireland, still visible as raised rings in pasture fields. This one in Castletown was recorded on the Ordnance Survey maps of 1841 to 1842 and again on the revised edition of 1898, suggesting it was still legible in the landscape through the Victorian period. By 1977, when the Geological Survey of Ireland captured the area in aerial photographs, the enclosure showed up clearly as a cropmark or soil shadow, the kind of ghost an earthwork leaves behind after ploughing has levelled it. At some point between the late nineteenth century and the late twentieth, the banks were removed altogether. C. Toal's North Kerry Archaeological Survey, published in 1995, placed it east of another recorded monument in the area and confirmed that no surface trace survives.

What remains is essentially a coordinate and a cartographic memory. The 1841 to 1842 Ordnance Survey maps, produced with remarkable precision during a period of intense state mapping of Ireland, captured the rath at a moment when it was still a feature of the farmed landscape. That it persisted into the 1898 revision and then into aerial photography before vanishing entirely makes it a small case study in how quickly a monument of over a thousand years can disappear once the farming economics change.