The Underground is an electric railway system that covers much of The London Greater London and some neighbouring areas It is the world's oldest underground system. and is one of the largest in terms of route length services began on January 10, 1863 on the Metropolitan Railway, most of that initial route is now part of the Hammersmith& City Line. Despite its name. about 55% of the network is above ground Popular local names include the underground and, more colloquially, the Tube, in reference to the cylindrical shape of the system's deep-bore tunnels The Underground serves 275 stations and runs over 408 km(253 miles) of line There are a number of former stations and tunnels that are closed in 2005-2006, 971 million passengers used the Underground and for the first time ever in 2006-2007. over one billion passengers were recorded. As of March 2007. just over 3 million passengers use the Underground each day. with an average of 34 million passengers on weekdays. Since 2003, the Underground has been part of Transport for London mIL). which also administers Greater London's buses, including the famous red double-deckers, and carries out numerous other transport-related functions. The former London Underground Limited was a subsidiary of London Regional Transport. a statutory corporation.