A subcircular enclosure lies buried beneath the fields at Greenville, its presence detectable not by any upstanding earthwork but by the faint discolouration of crops above its buried ditches. Cropmarks of this kind appear when differential soil moisture, caused by underground features such as filled ditches or foundations, affects the growth of vegetation above them, making the outline of a long-vanished structure briefly legible from the air. This one was only confirmed as visible on a Google Earth image captured on 14 July 2018.

The enclosure measures roughly 40 metres on its longer axis and about 34 metres east to west, and appears to have been defined by two fosses, that is, ditches cut into the ground to demarcate and defend a settlement. The inner fosse can be traced from the south-southwest, around the west, and continuing to the northeast, while the outer fosse is only clearly readable between the northwest and northeast. Along the southeast to southwest perimeter, the line of the enclosure has been absorbed into an existing field bank, meaning the modern agricultural landscape has quietly inherited the boundary of something much older. The site was first reported by Simon Dowling, and its double-ditched form is consistent with the enclosed farmsteads that were common features of the Irish countryside from the early medieval period onward.

Because the enclosure survives only as a cropmark, there is nothing to see at ground level. The site is invisible to anyone walking the field and meaningful only in aerial or satellite imagery taken under the right conditions of crop growth and dry weather.