Tap the stone surface of a roughly rectangular stone-lined area inside an ancient enclosure at Rahealy, and it gives back a sound that should not be there: the dull resonance of empty space underground. That acoustic detail, small and easy to miss, points to the likely presence of a souterrain, an artificial underground passage or chamber typically built during the early medieval period, often used for storage or refuge, and constructed with dry-stone walling and roofing slabs.

The enclosure surrounding this feature is a univallate cahir, meaning a roughly circular stone-walled fort defended by a single stone bank rather than earthen ramparts. The bank is now grass-covered, but the interior sits at a noticeably higher level than the surrounding land, which is itself a clue to centuries of accumulated occupation and debris. In the north-western sector of the enclosure stands a mound measuring approximately five metres by nine metres and around eighty centimetres in height. Its significance may be read from a much earlier map: the Ordnance Survey mapping of 1841 to 1842 marks the spot with the word "Cave", suggesting that local knowledge of something underground here predates modern archaeological investigation by well over a century. The south-eastern portion of the enclosure holds the stone-lined rectangular area whose hollow response underfoot lends the whole site its quietly unsettling quality. The site was recorded and described by C. Toal in the North Kerry Archaeological Survey, published in 1995.

The enclosure sits in the middle of a long, narrow field, visible as a distinct raised circular form against the surrounding farmland. The grass-covered bank traces the perimeter, and the interior mound is legible as a slight but definite swelling in the ground. The hollow-sounding stones to the south-east are the most immediate point of interest, though the chamber itself, if one does indeed lie beneath, remains unexcavated and out of sight.