There is no mound, no visible stonework, and nothing to distinguish this particular patch of farmland from the surrounding countryside. What exists here is detectable only from the air, as a cropmark, the faint differential in how crops grow over buried features where disturbed soil and ancient ditches retain moisture differently from the undisturbed ground around them. It is, in other words, a place that reveals itself only under the right conditions and only to those looking at the right scale.

The site was identified by Simon Dowling from aerial photography captured in November 2011. What the imagery shows is a roughly circular enclosure measuring approximately 34 metres north to south and 40 metres east to west, itself sitting inside a larger oval-shaped cropmark some 58 metres by 92 metres. The relationship between these two concentric forms is the most intriguing aspect of the site. Double-ditched enclosures of this kind are known elsewhere in Ireland and are often associated with early medieval settlement, though the Ballymack site has not been excavated and no date has been assigned to it. The northern arc of the outer oval appears to have been cut across by a later field boundary running east to west, meaning that at some point in the landscape's more recent history, a farmer drew a line straight through something they could not see and may not have known was there.