This one in Ballygow, County Wexford, is visible only from the air, and only under the right conditions. A large oval enclosure, roughly 75 metres along its north-west to south-east axis and about 60 metres across, shows up as a cropmark on aerial photographs, its outline traced by a single narrow feature buried beneath the soil of a low north-south ridge.

Cropmarks like this one form when buried ditches or banks affect the growth of whatever crop is planted above them. Filled-in ditches tend to retain more moisture, producing lusher, taller growth; compacted banks have the opposite effect. From ground level, nothing is visible. From altitude, especially in dry summers when the contrast is sharpest, the hidden geometry of an old enclosure can suddenly resolve itself against the surrounding field. The Ballygow enclosure sits on the crest of a low ridge, a position that would have made sense to whoever constructed it, offering a degree of elevation and visibility over the surrounding landscape. The oval shape and the scale are consistent with the kinds of enclosures, sometimes associated with early settlement, agricultural activity, or ceremonial use, that were a common feature of the Irish landscape across a long stretch of prehistory and the early medieval period, though nothing in the available record pins this particular example to a specific date or function.