This one, in the low-lying pasture near Rogerstown estuary in north County Dublin, offers nothing to the eye at ground level. What archaeologists believe may be a roughly circular enclosure of around 100 metres in diameter exists, for the most part, only as a curve in an aerial photograph taken in 1971, and a corresponding bend in a nearby field boundary that has quietly preserved the ghost of something older beneath it.

The site came to attention through aerial survey reference FSI 587/588, in which a curving cropmark, the kind of faint discolouration in growing crops that can betray buried ditches or banks to a camera pointed downward from altitude, hinted at a substantial enclosure below the surface. Cropmarks form when buried features affect the moisture and nutrients available to crops above them, causing subtle differences in growth that are invisible at ground level but readable from the air under the right conditions. The enclosure was recorded in the Nethercross barony, a historical administrative division of County Dublin, and the site was later incorporated into Turvey Nature Reserve. A geophysical survey carried out under licence number 06R0154 was subsequently undertaken to try to establish the extent and precise location of the feature, but the results were inconclusive. No clear responses consistent with an enclosure were detected; the isolated signals that did appear were attributed by the surveyor to natural variations in the subsoil rather than to any buried structure (Leigh, 2006).

Turvey Nature Reserve lies close to Rogerstown estuary, a significant estuarine habitat on the north Dublin coast, and the reserve itself is accessible to walkers. Anyone visiting with the enclosure in mind should not expect to find a marked feature or any visible trace of it on the ground; the site remains unconfirmed, and its archaeology is, for now, suspended somewhere between the suggestive and the inconclusive. The most honest thing to look for is the field boundary itself, that slight curve in the landscape which may, or may not, remember the edge of something that was once deliberately made.