When McCaffrey catalogued it in 1952, the site was identifiable as a roughly circular enclosure about thirty metres across, shaped by two concentric earthen banks with a fosse, or ditch, running between them, and a narrow entrance gap of around two metres on the eastern side. Today, only the inner bank survives, tracing an arc from east through south to west, the outer bank long since lost to farming, erosion, or simple time.

What gives the site an additional layer of interest is the presence of a souterrain in the western half of the interior. A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement in Ireland, and generally interpreted as a place of refuge, cool storage, or both. Their appearance within or beside ringforts and earthen enclosures is well documented across the country, and Pollnagarragh fits that pattern neatly, even if much of the enclosure itself no longer stands to full height. The combination of a defended enclosure and an underground chamber points to a site that once functioned as a farmstead of some consequence, probably during the early medieval period, when such arrangements were a common feature of the Irish countryside.