The Nordland Line in Norway is 453 miles long - the longest in the country. Built to transport Norway's greatest natural resource – iron ore – the first section opened in 1882. The Nordland crosses the Arctic Circle and nowadays it carries a combination of commuters, long-haul passengers and freight trains. But it has a darker, mysterious past.

Under Nazi occupation, Hitler used thousands of slave labourers to extend the line towards Kiruna in Sweden. It became, in effect, one huge slave camp where many thousands died in terrible conditions. Nordland became an invaluable part of the Nazi war machine. Nordland also saw one of the most audacious and daring raids of World War Two, when US ski - paratroopers managed to destroy a section of the line, reducing its usefulness to Germany.