Not demolished, not filled in, but simply gone from view, leaving only a saucer-shaped depression in the ground, roughly six feet across, that one early observer noted looked like a cave opening. That faint hollow is the sole surviving hint of what lies, or once lay, below.

Souterrains are underground stone-built passages or chambers, constructed during the early medieval period in Ireland, typically associated with ringforts. Ringforts themselves, circular enclosures defined by earthen banks and ditches, were the dominant farmstead type of early medieval Ireland, and souterrains beneath them served as storage spaces or places of refuge. The souterrain at Barrahaurin sits within one such enclosure, and the relationship between the two is entirely in keeping with that pattern. Beyond the note that a depression of around six feet in diameter was observed at the centre of the fort, described by an investigator recorded only as PJH, no visible surface trace now remains. Whether the passage beneath has collapsed, silted up, or simply been obscured over time is not recorded.