Central line (London Underground) Central line (London Underground) The Central line is a London Underground line that runs through central London, from , Essex, in the north-east to and in the west. Coloured red on the Tube map, the line serves 49 stations over , which makes it the longest Tube line. It is also one of only two lines on the Underground network to cross the Greater London boundary, the other being the Metropolitan line. One of London's deep-level railways, Central line trains are smaller than those on British main lines. The line was opened as the Central London Railway in 1900, crossing
London Underground well as many of London's bus and tram operators. Only the Metropolitan Railway, along with its subsidiaries the Great Northern & City Railway and the East London Railway, and the Waterloo & City Railway, by then owned by the main line London and South Western Railway, remained outside the Underground Group's control. A joint marketing agreement between most of the companies in the early years of the 20th century included maps, joint publicity, through ticketing and UD signs, incorporating the first bullseye symbol, outside stations in Central London. At time, the term Underground was selected from three other proposed names;