The Siegfried Line, known in German as the Westwall, was a German defensive line built during the 1930s (start 1936) opposite the French Maginot Line. It stretched more than 630 km (390 mi); from Kleve on the border with the Netherlands, along the western border of Nazi Germany, to the town of Weil am Rhein on the border to Switzerland – and featured more than 18,000 bunkers, tunnels and tank traps.