A cropmark, the kind of ghostly outline that appears in aerial photographs when buried features cause crops above them to grow at slightly different rates, reveals a circular enclosure roughly a hundred metres across at its widest north-to-south extent. That is a considerable diameter, and size, in the archaeology of early Ireland, tends to carry meaning.

Large circular enclosures of this kind are frequently associated with early Christian ecclesiastical sites. The circular boundary, or vallum as it is sometimes called in monastic contexts, would have defined sacred ground, separating the religious community within from the secular world outside. Many of Ireland's early medieval churches, some now entirely forgotten, were founded within exactly this kind of enclosure. The name Ballymanus itself offers little immediate guidance, but the placename element "Church" assigned to this site points to a long-standing local memory of religious association, even where physical remains have long since disappeared. Complicating the picture slightly is a small quarry that has cut into the north-north-west quadrant of the enclosure, a reminder that agricultural and extractive activity has been working away at the site for some considerable time.