Hardknott Pass is a pass that carries a minor road between Eskdale and the Duddon Valley in the region of Cumbria, England, in the Lake District National Park. The road approaching the pass vies with Rosedale Chimney Bank in North Yorkshire for the title of steepest road in England with both having a gradient of 1 in 3 (about 33%).
The Romans originally built a road over the pass in the 2nd century to link the coastal fort at Ravenglass with their garrisons at Ambleside and Kendal. The Romans called this road the Tenth Highway. It reaches a height of 393 m (1,289 ft) at the top of the Hardknott Pass before descending steeply to the Duddon Valley and then ascending and descending the Wrynose Pass (also 393 m) on its way to Ambleside. The road fell into disrepair after the Romans left Britain in the early part of the 5th century, although it remained as an unpaved packhorse route throughout the centuries.
The War Office used the area for tank training during the Second World War and this completely destroyed the ancient track. After the war a decision was made to repair the damage and rebuild the road with a tarmac surface to give a direct motor route between Ambleside and Eskdale for the first time. However, the Roman route and the modern road do not generally coincide, the Roman route lying generally to the north of the modern road west of the summit, and to the south on the other side.
Heavier vehicles are advised not to use the pass. The pass itself has a series of hairpin bends in which the tarmac has become quite smooth in places. Drivers are expected to give way to oncoming traffic that is ascending the pass, as advised by the Highway Code. The pass can be closed for long periods in the winter months as ice makes the bends treacherous.
As the pass leaves Eskdale it passes Hardknott Roman Fort at a height of around 200 metres (660 ft), and there are a few parking places for drivers who want to stop and look at the ancient site. At the top of the pass the road goes between the fells of Hard Knott and Harter Fell; once again there are a few parking places which are usually used by fell walkers who wish to start their walk at a height of 400 metres (1,310 ft) or by tourists who want to admire the views, which on a clear day includes the Isle of Man in the Irish Sea.