Lisleitrim fort in County Monaghan belongs to that category: formally noted in 1967, removed in 1968. A year was all that separated its documentation from its disappearance.

The fort sat just south of the summit of a drumlin, one of those smooth, oval hills of glacial till that ripple across the Monaghan landscape in their thousands. It still appeared on the 1907 Ordnance Survey six-inch map, named in the distinctive gothic lettering the OS reserved for antiquities, a cartographic signal that something old and worth marking once occupied the spot. When surveyors examined it in 1967, they found a D-shaped enclosure roughly forty metres across its longest axis and thirty metres across its shorter one, defined by a low earthen bank on its western side and a scarp to the east. A scarp, in this context, is simply a steep natural or cut slope used as a boundary, doing the work that a built bank might do elsewhere. The bank itself was modest, its external face rising to about two metres, its internal face barely reaching knee height. There was no visible fosse, the outer ditch that typically accompanies an earthwork enclosure, and no identifiable original entrance. A road bank had already cut across the northern side. The following year, the monument was removed entirely.