The only evidence that something once stood at Ballyheen comes from the air, where differences in soil moisture and crop growth reveal the ghost of a circular enclosure roughly forty metres across. This kind of mark, known as a cropmark, appears when buried ditches or banks cause overlying crops to grow at slightly different rates, producing patterns invisible at ground level but readable from above. The Ballyheen enclosure was captured in an aerial photograph taken in July 1989, and what it shows is a fosse, a defensive or boundary ditch, describing a near-complete circle in the soil.

What makes this particular site a little more puzzling are two parallel linear cropmarks that cut across the eastern half of the enclosure's interior on a rough north-south axis, before turning sharply eastward just outside the fosse itself. Whether these lines represent a trackway, a field boundary, a drainage feature, or something else entirely is not recorded, and their relationship to the enclosure, whether contemporary with it or added later, is unknown. Circular enclosures of this general type are common across Ireland and often associated with early medieval settlement, though without excavation it is impossible to say anything more specific about date or function at Ballyheen. The ditch may once have surrounded a farmstead, a ceremonial space, or something else entirely.