First recorded on the 1835 Ordnance Survey map, this earthen enclosure commanded impressive views across the north and north-west of the landscape. By the time cartographers returned for their second edition, road improvements in the mid-19th century had already begun eating away at the ancient structure, and by 1905, it had completely vanished from maps and memory.

The site’s strategic location wasn’t accidental; it sat along what was likely the most direct route connecting the early medieval monastic sites of Kilmacrenan, Raphoe, and Derry, threading through a natural mountain pass northwest of Letterkenny. Archaeological excavations between 2002 and 2005, prompted by modern N56 road realignment works, revealed what centuries of ploughing and construction had hidden. Beneath two metres of dumped construction waste and topsoil, archaeologists uncovered the fort’s defensive ditch, which once curved around the settlement at depths of up to 1.4 metres. The ditch yielded a treasure trove of everyday medieval life: charred hazelnut shells, willow charcoal, animal bones, and even the preserved remains of a weevil, all dating to between AD 690 and 900.

What makes this site particularly poignant is how thoroughly it disappeared from the landscape. Where once an earthen bank rose from the excavated soil to protect the inhabitants within, only a line of mature ash trees remained to hint at its presence. The inner bank, constructed from the distinctive reddish-orange subsoil thrown up during the ditch’s excavation, survived as a mere 25-centimetre high mound buried deep underground. Today, traffic speeds along the N56 directly over where medieval Irish families once lived, worked, and defended their small corner of Donegal, following almost the same ancient route that connected the region’s spiritual centres over a millennium ago.