The enclosure exists, for now, as a cropmark, a phenomenon that occurs when buried walls, ditches, or other buried features affect how the soil above them retains moisture, causing the crops growing overhead to ripen or wither at different rates from the surrounding field. From the air, those variations in colour and vigour trace the outlines of what once stood, or was dug, below.

The shape recorded here measures approximately 41.5 metres along its northwest to southeast axis and around 35 metres across the other way, giving it a roughly rectangular footprint of modest but meaningful size. It was identified from aerial photography taken in May 2003. Beyond that, the record is silent. There is no confirmed date, no excavation report, no firm identification of what function the enclosure served. Rectangular enclosures of this kind in the Irish midlands and south can belong to many different periods and purposes, from early medieval farmsteads to post-medieval field systems, and without ground investigation the Ballynahow example sits in a category of quiet uncertainty that is actually rather common in Irish landscape archaeology. Many such sites are known only as marks in a crop, photographed once and then left to the land.