The structure is a souterrain, an underground stone-built tunnel typically associated with early medieval settlement in Ireland, used variously for storage, refuge, or ventilation of domestic spaces. This one was backfilled in the early twentieth century and has sat undisturbed beneath suburban lawn ever since.

According to local information, the passage was of dry-stone construction with lintel roofing, meaning flat stones laid horizontally across upright walls to form a ceiling rather than an arch. It ran on a northwest to southeast axis for approximately fifteen metres, a respectable length that suggests a reasonably substantial early settlement in the vicinity. The site sits on gently elevated ground, which is broadly consistent with the kind of position early medieval communities tended to favour, offering a degree of natural drainage and outlook. Beyond what local memory has preserved, the details of who built it, when, and in connection with what broader settlement remain unrecorded.