The souterrain, an underground chamber or tunnel typically built during the early medieval period as a place of refuge or storage, was reportedly blocked up sometime in the early twentieth century. Since then, it has left no mark on the surface. Nobody now knows precisely where within the rath it sits.

The rath itself, a ringfort of the kind built by farming communities across Ireland from roughly the fifth to the twelfth centuries, provides the immediate context. These enclosures, usually defined by an earthen bank and ditch, frequently contained souterrains beneath their floors or inner banks. At Carrowndangan the association between the two survives only as local tradition. The blocking of the passage, whenever exactly it happened, erased the physical evidence and left the memory of it floating free of any fixed point. That combination, a known thing in an unknown location, gives the site an odd quality. It is recorded but essentially inaccessible, present in the landscape and absent from it simultaneously.

There is nothing to see at ground level, and the exact position of the souterrain within the rath remains uncertain. For a visitor, the interest is less in what can be observed than in what the site represents: a piece of local knowledge that survived the twentieth century even as the physical entrance it described did not.