Overview
Glendun is one of the nine Glens of Antrim, and the brownest: the River Dun that carved it runs the colour of strong tea, stained by the peat bogs on the upper slopes of Slieveanorra. Its Irish name, Gleann Abhann Duinne, means exactly that – “glen of the brown river”. A steep-sided U-shaped valley gouged by Ice Age glaciers, it drops to the Atlantic between the seaside village of Cushendun and the quiet hamlet of Knocknacarry, within the Antrim Coast and Glens Area of Outstanding Natural Beauty. It is a quiet glen, with a single-lane road and little traffic.
The Glendun Viaduct
The glen’s most striking feature is the three-arch stone Glendun Viaduct, known locally as the Big Bridge. The listed Glendun Viaduct carries the road over the valley. Its stone arches were built between 1834 and 1839 as part of the coastal road project designed to connect Ballycastle with Ballymena. Civil engineer William Bald designed the structure, with Sir Charles Lanyon acting as surveyor. Master builder Mr Bowells of County Monaghan, assisted by craftsmen from County Donegal, quarried stone from the cliffs at Layde, shipped it to Cushendun, and carted it up the valley.
The road is narrow and shared with farm traffic, so leave it and any field entrances clear and do not stop where you would block them.
A walk at Cushendun
For a public walk, start in Cushendun and use the National Trust’s visitor information for parking and routes. The village sits beside the river mouth and has a harbour and beach. Keep to public paths.
History & Local Lore
The glen’s history stretches back centuries, shaped by native Irish families and Hebridean Scots settlers. It also played a role in a pivotal 16th-century conflict. In the late 1500s, Sorley Boy McDonnell used the glen’s secluded, peat-filled terrain to launch a night-time ambush on an English cavalry force at the Battle of Orra. The English troops became mired in the swampy ground and were defeated, with several commanders killed.
Today, the glen’s stone walls, ruined cottages and quiet lanes reflect generations of agricultural life that have shaped the landscape.
Wildlife & Nature
Birdwatchers will find the valley’s mixed woodland and riverbanks rich with species including dippers, treecreepers, jays, redstarts and occasional golden plovers. In autumn, the canopy shifts to amber and crimson, while winter brings a moody, atmospheric quality to the upper slopes.
Planning a visit
Check the National Trust page above for parking and routes in Cushendun. Mobile signal can be patchy in the valley, so carry a map or download offline directions before setting out.