Less remarked upon is the fact that the mountain also carries the trace of an ancient enclosure, a feature recorded among its monuments but not yet widely examined in public-facing sources. Enclosures of this kind, essentially bounded areas defined by earthen banks, ditches, or stone walls, appear across the Irish landscape in contexts ranging from the prehistoric to the early medieval, sometimes serving as settlement boundaries, sometimes as stock enclosures, and occasionally as markers of ritual or ceremonial space.

Knocknarea itself has been a focus of human activity for thousands of years. The summit cairn, Miosg
abha
n na R
a
ona, is thought to date to the Neolithic period, and the broader mountain is understood to have formed a significant place in the prehistoric landscape of the Cúil Irra peninsula, a region unusually dense with megalithic remains. An enclosure on or near such a site sits within that layered context, though without detailed excavation or survey data available in the public domain, its precise date and function remain open questions. The mountain's limestone plateau and the visibility it commands over Sligo Bay and the surrounding lowlands would have made it meaningful to communities across many different periods.