An archive of photographs has revealed the engineering feat of building the M6 in Cumbria 50 years ago.
It is one of the highest stretches of motorway in the country, covering 36 miles (57.9km) between Lancaster and Penrith.
The road, which incorporates the Lune Gorge, was opened on 23 October 1970.
Photographs of the construction of the motorway, by John Laing Construction Ltd, have been preserved in a special Historic England archive.
At the time, it was the highest section of motorway in the country at Shap, at 316m (1037ft) above sea level.
The surveys for the M6 through Cumbria were done from the air, which was a first for the UK.
Work on the Lune Gorge section of the road, between Killington and Tebay, began in October 1967 with construction carried out by civil engineering specialists John Laing Construction Ltd.
At the time the weather and ground conditions were some of the most challenging faced by UK engineers, according to Highways England, which operates the motorway.
Almost a thousand road workers were involved in the project, which had five separate construction contracts making up the new Lancaster to Penrith route.
Mike Gellatley, a fellow of the Institution of Civil Engineers and former London Underground chief engineer, remembered working on the project which was "a constant battle against the elements".
"Residents in the area were initially sceptical about the motorway but it totally transformed journeys," he said.
"In the days before the M6, a journey up to the to the far north and Scotland was a torturous adventure with vehicles often having to queue in winter to get past snow along the A6 at Shap."
The Roger Howe Bridge over the River Lune was built for the re-routed A685 during the construction of the M6, through the Lune Gorge.
Keith Little, of Cumbria County Council, called the motorway a "vital part" of the development of the county's transport network.
"It made the county more accessible to the rest of the country and has enabled local businesses and residents to trade, travel and connect with the wider region," he said.
The Lancaster to Penrith M6 was officially opened by Transport Industries minister John Peyton on 23 October 1970.
At 236 miles (379km), running from Rugby in Warwickshire to the Scottish border, the M6 is the longest motorway in the country.
It was not completed until 2008 when the Highways Agency finished converting the A74 between Carlisle and Gretna Green.
Archive copyright: Historic England/John Laing Photographic Collection