At Aglish in County Kerry, a souterrain, an underground stone-lined passage typically built during the early medieval period as a place of refuge or storage, is known only through local memory. No stonework breaks the surface, no hollow in the ground betrays its outline, and yet the tradition of its existence has been considered credible enough to record.

The souterrain is said to lie within a rath, a circular earthen enclosure of the kind that was once a common feature of the Irish countryside, serving as a farmstead or defended homestead from roughly the fifth to the twelfth century. Souterrains were frequently constructed within such enclosures, and the pairing is well established across Ireland. What is unusual here is the complete absence of physical remains. Whether the passage collapsed inward over the centuries, was quarried for its stone, or simply lies too deeply buried to leave any surface trace, is unknown. The record rests entirely on what people in the locality once knew or believed.