}} The Metropolitan line is part of the London Underground. It is coloured in Transport for London's (TfL) Corporate Magenta on the Tube map and in other branding. It was the first underground railway (or subway) in the world, opening on 10 January 1863 (however, parts of that initial section are no longer served by the Metropolitan line, but by the Hammersmith & City, District and Circle lines). The main line runs from Aldgate in the City of London to Amersham, with branch lines to Uxbridge, Watford and Chesham. For the initial section of the line the rails are underground for much of the way; beyond Baker Street, at Finchley Road the line runs in the open. Out of the 34 stations served, only 9 are underground. It is the oldest line and initially covered the bulk of the Underground system