This one is remarkable for what it no longer does. At Castletreasure in County Cork, a souterrain, an underground stone-lined passage typically associated with early medieval settlement and used for storage or refuge, was recorded and then lost before anyone could properly examine it. No foundations break the surface, no hollow in the ground marks the spot. Whatever was there is simply gone.

The souterrain was discovered within what may have been a ringfort, the circular earthwork enclosures that served as farmsteads across Ireland from roughly the early medieval period through to the Norman arrival. Ringforts are common enough in the Cork landscape, but this one carries the designation "possible", suggesting its own outline was already uncertain. The souterrain itself was noted in topographical files held at University College Cork, yet it was destroyed before any formal investigation could take place. The sequence is a familiar and frustrating one in Irish archaeology: a feature comes to light, usually during construction or agricultural work, and is gone before excavation tools arrive.