Complex sentence: Falun is located in the Bergslagen district, and the mining area of the Great Copper Mountain in Falun has been declared a UNESCO World Heritage Site, which also was the name of the mining company of Falun, is today a part of Stora Enso.
Split into simpler sentences: Falun is located in the Bergslagen district, and the mining area of the Great Copper Mountain in Falun has been declared a UNESCO World Heritage Site. Stora Kopparberg ("Great Copper Mountain"), which also was the name of the mining company of Falun, is today a part of Stora Enso.