At Tullahennel in County Kerry, the Ordnance Survey of 1841 to 1842 recorded a circular enclosure on the landscape, the kind of feature that would have been recognised at the time as a rath or ringfort, an earthen-banked enclosure typically dating to the early medieval period and used as a defended farmstead. By the time the later edition of the same survey was produced, that mark had quietly disappeared from the record. No mound, no ditch, no visible trace remains on the ground today.

Raths are among the most common archaeological monuments in Ireland, with tens of thousands once dotting the countryside. Their gradual erasure from the landscape over the past two centuries has been steady and largely unremarked, driven by agricultural improvement, land drainage, and the pressure to bring every usable acre into cultivation. The gap between the two Ordnance Survey editions at Tullahennel tells its own compressed version of that wider story: a structure that had survived in some recognisable form for perhaps a thousand years was gone within a generation of first being formally recorded. C. Toal's North Kerry Archaeological Survey, published in 1995, noted the site's existence and its disappearance, preserving at least the documentary outline of something the ground itself no longer holds.

There is nothing to see at Tullahennel now, which is precisely what makes the site worth knowing about. The 1841 to 1842 map becomes, in effect, the only surviving witness.