That is, in a sense, the point. Somewhere beneath the ground in the Farranmanagh district of County Kerry, there once ran a souterrain, an artificially constructed underground passage or chamber, typically built during the early medieval period and associated with nearby ringforts. This one has left no trace on the surface whatsoever, its existence now preserved only in the language of a mid-twentieth-century field report.

A rath, or ringfort, the type of enclosed settlement defined by earthen banks and ditches that once dotted the Irish countryside in their tens of thousands, stood here at Ardywanig, and within or beneath its enclosing rings ran what was recorded in 1948 as "the great souterrain." That description comes from the Minutes of the Co. Kerry Field Club, volume two, where whoever walked the site in that decade still found it notable enough to warrant the superlative. The rath itself is recorded separately. The souterrain it once contained is gone, or buried so completely that it registers as absence rather than archaeology. By the time the site was formally documented in more recent years, no visible remains could be identified at all.

What makes a site like this worth noting is precisely that gap between a recorded description and what the ground now offers. Someone in the 1940s stood at Hogan's rath in Farranmanagh and saw, or entered, something substantial enough to call great. Whatever that was, whether the passage had partially collapsed, was filled in, or simply settled deeper into the earth over the intervening decades, it is no longer accessible in any physical sense.