At Knockane in County Kerry, the 1842 Ordnance Survey map records both a circular enclosure and, at its centre, the single word 'Cave', the period term for what archaeologists now call a souterrain. A souterrain is an underground stone-lined passage or chamber, typically built during the early medieval period and associated with nearby ringforts; they were used variously for storage, refuge, or both. By the time the later edition of the OS map was produced, neither the enclosure nor the cave merited a mark. Today, no surface trace of either survives.

The circular enclosure, catalogued as KE014-058, would almost certainly have been a ringfort, the kind of enclosed farmstead that dots the Irish landscape in the thousands. The pairing of ringfort and souterrain was common across early medieval Ireland, and Kerry has its share of both. What makes this particular site more poignant than most is the precision of its disappearance. The 1842 survey caught it at what may have been its last legible moment, a fort still visible enough to draw and a subterranean feature still known locally enough to name. Somewhere between that survey and the next, the enclosure was levelled, the cave forgotten, and the ground closed over whatever lay beneath.