What appears on the ground as little more than a subtle rise or dip in the soil resolves, when seen from altitude, into the unmistakable curve of an ancient enclosure, with what looks like an entrance gap opening to the north-west.

Circular enclosures of this kind are scattered across Ireland and represent one of the country's most enduring and ambiguous monument types. They may have served as settlement sites, stock enclosures, or ceremonial spaces, and their dates range across several millennia, from the Bronze Age through to the early medieval period. Without excavation, the function and age of the Kilmullin example remain open questions. What is known is that it came to light through the careful reading of orthophotography, aerial images corrected for distortion to give an accurate overhead view of the terrain, by a local observer, Ms Faith Bailey, who recognised the feature and brought it forward for recording.