When did the first subway open?

The Metropolitan Railway opened on 10 January 1863 as the first underground railway carrying passengers. The original line ran about 6 kilometres between Paddington and Farringdon and used steam locomotives, which filled the tunnels with smoke and steam. Despite the fumes, it was an immediate success and carried tens of thousands of passengers on its first day. The line was built using a cut-and-cover method, digging a trench along streets and then roofing it over. Electric trains later replaced steam, and the network grew into the sprawling system Londoners simply call the Tube.