The only evidence of its existence came from the air, on a July day in 1990, when differences in crop growth across the soil revealed its outline as a cropmark, the ghostly imprint of a fosse, or defensive ditch, that once defined its perimeter. Cropmarks form when buried features such as ditches or walls affect the moisture and nutrients available to growing crops above them, causing subtle variations in colour and height that can only be read from altitude.

The aerial photograph, taken on 14 July 1990 and catalogued as GB90.BN.12, captured a circular form defined by what was once a surrounding ditch. What lay inside, and who made use of it, the photograph cannot say. Circular enclosures of this kind are found widely across Ireland and range in date and function from prehistoric settlements to early medieval farmsteads, though nothing in the available record pins this particular example to a specific period or purpose. What the photograph does confirm is that this enclosure was not alone in the landscape. A second enclosure sits approximately 115 metres to the south, suggesting that this part of Brackin was, at some point, a more organised or inhabited place than the present tillage fields would suggest.