What gives it away is a phenomenon known as a cropmark, where buried ditches and features cause the plants growing above them to mature at a different rate or colour than the surrounding crop. In this case, the buried ditch shows as a positive cropmark, meaning the vegetation above it grows more vigorously, likely because the filled-in ditch retains more moisture than the compacted soil around it. The result, visible in aerial and satellite imagery, is a ghost of an ancient boundary pressed into the surface of a field.

The enclosure was identified and recorded by Tom Condit, with the record uploaded in April 2021. It sits roughly 1.1 kilometres west-southwest of a cluster of known monuments in the nearby Springhill townland, which itself centres on a related enclosure, suggesting this part of north Dublin was once a fairly busy landscape of enclosed settlements or ceremonial sites. The Middletown example is subcircular in plan, measuring approximately 27.4 metres north to south and around 35 metres east to west, defined by a ditch roughly 1.9 metres wide. A ditch-defined enclosure of this type is a common form in Irish archaeology, often associated with early medieval ringforts or prehistoric settlements, though no period has been confirmed for this site. More intriguingly, the Apple Maps imagery appears to show two outer palisade trenches, the kind of narrow slots into which upright timber stakes would once have been set, running along the southern perimeter outside the main ditch. No clear entrance gap has been identified in the bank.

The site lies in a large arable field with an unnamed east-west stream, a tributary of the Mayne River, running approximately 180 metres to the south. There is nothing to see on the ground, and access would require permission from the landowner. The imagery that revealed the site was captured in June 2018, when crop growth conditions happened to be right for the marks to show clearly. Anyone interested in exploring it further would do best by consulting the Google Earth or Apple Maps coverage from that date, where the outline of the ditch and the possible palisade trenches are legible enough to trace with some patience.