The crossing of the Alps is a key issue at national and international levels, as the European continent is at places divided by the range. Since the beginning of industrialisation Switzerland has improved its transalpine network; it began in 1882, by building the Gotthard Rail Tunnel, followed in 1906 by the Simplon Tunnel and 1913 by the Lötschberg Tunnel, and more recently, in 2007, by the Lötschberg Base Tunnel. The 57.1-km long Gotthard Base Tunnel, the longest railway tunnel of the world, opened in 2016 and provides a direct flat rail link through the Alps.