There is no depression in the ground, no telltale hollow, no protruding stonework; the surface gives nothing away. That absence is itself a kind of archaeological fact.

A souterrain is an underground passage or chamber, typically constructed during the early medieval period in Ireland, often by lining a trench with drystone walling and capping it with large flat slabs before backfilling. They are commonly found within ringforts, the circular earthen or stone enclosures that dot the Irish countryside in their thousands and represent the farmsteads of early medieval families. This particular souterrain sits within one such ringfort at Knockskagh, and its existence was recorded by Webster in 1924. Beyond that single reference, the detail runs thin. No dimensions, no account of an entrance, no description of its construction. By the time the site was being formally catalogued, the souterrain had already vanished below the surface without visible trace.