It has no visible walls, no upstanding earthworks, and no obvious sign that anything is there at all, yet aerial photography taken in August 1996 revealed its outline with quiet precision: a roughly circular enclosure approximately fifty metres in diameter, betrayed only by the pattern of crops growing above it.

The phenomenon at work here is a cropmark, which forms when buried features such as ditches or walls affect the moisture and nutrients available to whatever is planted above them. Filled-in ditches retain more water, producing lusher, taller growth; buried stone foundations do the opposite, leaving the crop stunted and pale. From ground level, the difference is imperceptible. From the air in the right season, the buried geometry of an ancient structure can appear as sharply as if it had been drawn on the field. The Ballylarkin enclosure was captured in exactly this way, its circular form suggesting it may be a ringfort or an earlier enclosed settlement, though without excavation the precise date and function remain unknown. Circular enclosures of this scale are common across Ireland and typically range from the prehistoric period through to the early medieval, when ringforts served as farmsteads for individual families, the surrounding ditch and bank offering both a boundary and a degree of protection for livestock.