The label is matter-of-fact, as though the cartographers considered it unremarkable, yet what they were recording was almost certainly a souterrain, an underground passage built from carefully laid dry stone without mortar, of a kind constructed throughout early medieval Ireland. These passages were typically integrated into the earthen banks of ringforts, the circular enclosed settlements that served as farmsteads for much of the first millennium and into the early medieval period, and are thought to have functioned as places of refuge, cold storage, or both.

At roughly twenty metres in length, this is a substantial example. It sits within the northern to north-western sector of the ringfort, tucked into the raised bank, or berm, that defines the enclosure's boundary. The souterrain remained sealed and largely unexamined until the 1950s, when it was opened and recorded as a drystone-built passage. Beyond that brief moment of investigation, the historical record on this particular structure is thin, which in itself is not unusual; many such features across Ireland received only cursory attention when they came to light, and the 1839 map notation may represent the earliest formal acknowledgement that anything was there at all.