A cashel is a type of early medieval stone-walled enclosure, typically circular, built to protect a homestead or religious site. The underground structure recorded within it is a souterrain, a hand-built stone-lined tunnel or chamber, usually associated with early medieval settlement in Ireland and thought to have served for storage, refuge, or both. What makes this particular example unusual is not what it contains, but what it has become: a feature known only through a single early twentieth-century reference, its physical presence unconfirmed by any later eye.

The record of this souterrain comes from Lynch Athy, writing in 1913 to 1914, who noted its location within the cashel's interior, describing that interior as 'very uneven and rocky'. When the site was inspected in November 1982, no surface trace of the souterrain could be found. That gap of roughly seventy years between the original observation and the later visit is enough time for a shallow underground feature to become fully obscured, whether by vegetation, collapse, or accumulated debris across a rough and rocky surface. The cashel itself remains on record, but the souterrain it reportedly housed has, at least visibly, ceased to exist.