Great Dun Fell is a mountain pass at an elevation of 848 m (2,782 ft) above the sea level, located in Cumbria, England, in the Pennines mountain range. It’s the second-highest hill in England's Pennines.
At the summit of this hill there’s a radar station, key part of the Air Traffic Control system for Northern England and Southern Scotland. The construction of this radar station led to the repaving of a tarred road to the summit, which became Britain's highest road. To climb the summit, starting from Knock, the ascent is 7.29 km long and the elevation gain is 593 heightmeters, with an average percentage of 8.1 %.
The asphalted road to the Great Dun Fell is marked as private from just above the village of Knock, and not open to public motor vehicles. However, it is a bridleway until shortly before the radar station, so it is open to walkers, cyclists and horseriders. The climb can be split into several distinguishable sections – each no less grueling than the last as the gradient rises towards one-in-four.