There is nothing at ground level to suggest it is there at all, which makes its accidental discovery all the more striking. A local farmer came across it in the early 1950s, presumably during agricultural work, and what he found was a carefully constructed underground chamber that had waited, undisturbed and unrecorded, for centuries.

When National Museum of Ireland staff subsequently visited the site, they recorded it as an L-shaped souterrain, a type of underground passage, usually drystone-built, commonly associated with early medieval settlement in Ireland, where they were used for storage, shelter, or refuge. This particular example follows an L-plan, meaning the passage bends at an angle rather than running straight. The roof is formed from lintels, flat stones laid horizontally across the top, and the side walls are constructed in drystone, that is, without mortar. The passage measures approximately five metres in length, with a height of roughly 0.7 metres and a width ranging from 0.5 to 0.8 metres. It is a tight, low space. The fact that it sits on elevated upland ground is consistent with the broader pattern of early Irish settlement, where higher terrain offered both visibility and defensibility. No date has been formally established for its construction, but souterrains of this type are generally associated with the early medieval period, roughly the sixth to twelfth centuries.