| On May 3, 2018, Crown Prince Haakon and Crown Princess Mette-Marit of Norway attended the official opening ceremony of Rjukan-Notodden Industrial Heritage Site in Telemark. Rjukan-Notodden Industrial Heritage Site was added to UNESCO's World Heritage List in 2015 for the purpose of protecting the industrial landscape around Heddalsvatnet Lake and Vestfjorddalen Valley in Telemark state of Norway. The site is at the center of the factory which was built by Norsk Hydro for the purpose of producing fertilizer from atmospheric nitrogen. |
