Rjukan–Notodden Industrial Heritage

The Rjukan–Notodden Industrial Heritage Site in Telemark is a UNESCO-listed testament to the early-20th-century birth of hydroelectric power and industry, set beneath the sheer Gaustatoppen mountain. Norsk Hydro built hydropower plants, factories, transport lines and whole company towns here to fix nitrogen from the air into fertiliser using the region's mighty waterfalls. The Vemork plant above Rjukan later became famous as the target of the wartime 'heavy water' sabotage that hindered Nazi nuclear efforts; it now houses the Norwegian Industrial Workers Museum.