Beneath it, until recently, lay a souterrain, an underground stone-lined passage or chamber typically used in early medieval Ireland for storage, refuge, or both, and built without mortar using a technique known as drystone walling. That souterrain is now gone, levelled completely, leaving a site that is both archaeologically significant and, in a quiet way, quietly diminished.

The enclosure itself was recorded on Ordnance Survey maps as far back as 1842, and again on the 1916 edition, which additionally marked a 'cave' within its interior, that annotation almost certainly referring to the souterrain entrance. When the underground structure was finally uncovered, roughly a dozen years before the site was formally recorded in published survey work, it was described as an excellent example of drystone construction, the kind of careful, mortarless stonework that has survived elsewhere across Ireland for over a thousand years. The relevant survey, C. Toal's North Kerry Archaeological Survey, published in 1995, captured the site at a point when the souterrain had already been exposed but before it was destroyed. The sequence is a familiar and frustrating one in Irish archaeology: discovery, brief documentation, and then loss.