Around 1901, the city of Berlin planned to build an underground railway line below Friedrichstraße to connect the north to the south. Werner von Siemens also had plans for a north–south line, under Nobelstraße, at the same time, but permission for these was declined on the grounds that public transport should be in municipal ownership. Consequently, Berlin started the construction of the Nord–Süd-Bahn ("North–South railway") to link Wedding and Tempelhof (as of 2007, part of the U6), with a branch to Neukölln.