That the passage in question is an early medieval souterrain, an artificially constructed underground chamber or tunnel typically associated with ringforts and used for storage or refuge, seems almost beside the point when livestock are at stake. The blocked opening still sits within the interior of a ringfort at Killuppaun, its mouth now sealed by the boulder, which is itself supported on its south-eastern side by two regular limestone blocks that may once have served as roof lintels.

The souterrain does not exist in isolation. It sits inside a ringfort, the circular earthwork enclosures that were once the farmsteads of early medieval Ireland, and it has also been absorbed into a north-south field boundary that cuts across the monument. This kind of layering is not unusual in Irish rural landscapes, where older structures get quietly incorporated into later land divisions, but it does mean the archaeology has been reshaped by centuries of farming. The details of the closure come from local knowledge rather than any excavation or formal investigation, which gives the story a pleasingly matter-of-fact quality: an ancient underground structure, met with the same pragmatism as a broken gate.