Fort, Rossnaglogh, Co. Monaghan

Drumlins, those smooth elongated hills left behind by retreating glaciers, are a defining feature of the Monaghan landscape, and their summits were frequently chosen for exactly this kind of fortified enclosure. The choice was deliberate: elevation offered visibility, and the natural slope of the ground would have added to the defensive effect of earthworks already formidable in their own right.

The fort at Rossnaglogh is a bivallate ringfort, meaning it has two concentric circuits of earthen bank and fosse rather than the single ring more commonly encountered across Ireland. A fosse, in this context, is simply a ditch dug to accompany a bank, the excavated material typically thrown inward to build up the rampart above. Here, the inner bank survives to an external height of nearly three metres, and the outer bank reaches a comparable height, with its own fosse still visible to the north. The whole enclosure measures roughly 42 metres across. What makes the plan slightly unusual is that although the original entrance gap can still be identified through both the inner and outer banks on the east-northeast side, there is no surviving causeway connecting them across the intervening fosse, which would normally have formed the formal threshold of the site. A disused farm lane to the southeast appears to have absorbed part of the outer fosse over time, and a wide additional bank to the southwest and northwest suggests the site accumulated further boundaries as farming activity shaped and reshaped the ground around it.

The whole area is heavily overgrown, which makes the individual earthwork components harder to read on the ground than the measured dimensions alone might suggest. The banks are most pronounced on the exterior faces, where the drop away from the ridge is steepest, and a farm lane still runs along the outer edge to the northwest, offering a faint trace of how this ancient enclosure was eventually domesticated into an agricultural landscape.