Hilltop enclosure, Drumgavny, Co. Monaghan

The enclosure measures roughly 97 metres east to west and 93 metres north to south, making it a substantial feature by any reckoning, the kind of thing that becomes harder to explain the longer you look at it from the ground.

Drumlins, the smooth egg-shaped hills that characterise the landscape of Ulster and the midlands, were formed by glacial action and have long been favoured as sites for early enclosures, both because of the natural elevation they offer and the drainage their slopes provide. At Drumgavny, the enclosure is defined by an earthen bank that survives most visibly on the western side, where the base measures 4.5 metres wide and the external face still stands to a height of 2.5 metres. Beyond it lies a fosse, the ditch that typically accompanies such a bank, rounded in profile and roughly 1.6 metres deep externally at the western measurement point. Much of the rest of the perimeter has been worn down to little more than a scarp, a low natural-looking slope that only reveals its origins on close inspection, with hedging now doing the work the earthwork once did. A farm lane has been cut into the fosse along part of the southern side, and an external field bank has replaced the ditch along other stretches, so centuries of agricultural activity have quietly dismantled and repurposed much of the original structure. The most likely location of the original entrance is on the south-eastern side, where a modernised farm entrance now stands.