This one is remarkable for what it no longer does. On a west-facing slope of a ridge in the mixed farmland of Drumharsna, County Galway, there once stood a cashel, a type of ringfort built from drystone walling rather than earthen banks, roughly 38 metres in diameter. By the time anyone thought to look for it a second time, it was gone.

When the site was first recorded in October 1982, the cashel was already in poor condition. Its defining drystone wall had been partially absorbed by a later field wall along the north-west, and only a 2-metre gap on the eastern side appeared to be an original feature, likely the entrance. Inside the western half of the enclosure, a stone-filled hollow hinted at something beneath the surface: a probable souterrain, the kind of underground passage or chamber, typically stone-lined, that appears frequently in early medieval Irish settlements and may have served for storage or refuge. This feature had previously been noted by a researcher named McCaffrey in 1952. When surveyors returned in August 1985, however, field clearance had removed every visible trace of the cashel and the suspected souterrain alike. The landscape had simply closed over them.

What remains is essentially a coordinate and a description, the memory of a monument that was already fading when it was first formally observed, and which did not survive the few years between visits. The 1952 reference suggests the souterrain at least was known locally before the site attracted professional attention, which makes its subsequent disappearance all the more pointed. Early medieval cashels of this kind were typically built and occupied between roughly the fifth and twelfth centuries, and thousands once existed across Ireland. Many survive in some form; this one does not.