Ardmore Fort, in County Clare, is one such place: a small earthwork enclosure that was faithfully recorded by cartographers across successive editions of the Ordnance Survey, only to vanish almost entirely from the landscape within living memory.

The fort appears as a hachured feature, those short radiating lines used by OS surveyors to indicate the raised or hollowed profile of an earthwork, on both the 1840 and 1916 editions of the six-inch maps. By the time the twenty-five inch plan was produced in 1897, the enclosure was depicted as a modest structure, roughly ten metres along its northwest to southeast axis and just under eight metres across. That is small even by the standards of Irish ringforts, the circular or oval enclosed farmsteads that were built in their thousands across the country from the early medieval period onward. When fieldworkers visited in May 1999, the site lay in pasture on a south-facing slope, but no surface trace of the monument remained visible. A silage pit was identified as a likely cause of damage. Aerial imagery captured between 2005 and 2012 then showed the area had been planted with forestry, placing what little might have survived underground beneath a further layer of disturbance and obscurity.

There is nothing to see at Ardmore Fort today, and that in itself is worth noting. The site's trajectory, from named landmark to cartographic memory to forested ground, is a quietly common story in the Irish countryside, where agricultural pressures and land-use change have altered or erased a remarkable number of recorded monuments. The maps remain; the earthwork does not.