Roughly 44 metres in diameter, the outline of a circular enclosure shows up clearly on aerial photography, its curve tracing the ghost of a boundary that has long since been absorbed into the surrounding fields.

Circular enclosures of this kind are a recurring feature of the Irish countryside, and their origins can range widely across the centuries. Many are the remains of raths or ringforts, the enclosed farmsteads that were built in their thousands during the early medieval period, typically between the fifth and twelfth centuries. A ringfort usually consisted of an earthen bank and ditch surrounding a domestic space, home to a single family and their livestock. Over time, ploughing and land improvement erased the upstanding earthworks at countless such sites, leaving only the subtle crop and soil marks that aerial photography can reveal, particularly in dry summers when buried features affect how vegetation grows above them. Whether Clonyn's enclosure belongs to that early medieval tradition or to some other period entirely is not recorded; what is known is simply the shape it leaves behind, and the approximate scale of it.