At Bohernabredagh in County Cork, a depression roughly three metres inside the north-western bank of a ringfort marks the point where the roof of an underground passage has given way. That collapse is, in its quiet way, the most visible part of the whole structure.

Souterrains are stone-lined underground tunnels or chambers built during the early medieval period in Ireland, typically associated with ringforts, the circular enclosed settlements that once dotted the countryside in their thousands. They were used variously for storage, refuge, or concealment, and were constructed with corbelled or lintelled stone roofs that could, given enough centuries of neglect, eventually fail under the weight of the earth above them. When they do, the surface dips, and what remains is precisely the kind of subtle irregularity visible at Bohernabredagh. The ringfort here, a separate but related monument on the same site, provides the usual context: a defended homestead of the early Christian period, within whose bank or interior a souterrain would have served the household below ground as the fort itself served it above.