Colloquially known as the Tube, the London Underground was the first rapid transit system in the world, having begun operations in 1863.
 More than 3 million passengers travel on the Underground every day, amounting to over 1 billion passenger journeys per year for the first time in 2006.
The Underground has 11 lines, most of which connect the suburbs to Central London and together form a dense network in central London, linking major railway stations, central business areas and icons.
The Underground serves North London much more extensively than South London.
This is the result of a combination of unfavourable geology, historical competition from surface railways and the historical geography of London which was focused to the north of the River Thames.
South London is served primarily by surface railways (the majority of London Underground's route length is actually on the surface rather than in tunnel.)

Carrying nearly 50% of London's commuters, the Tube is the most heavily used mode of public transport in the area.
Colloquially known as the Tube, the London Underground was the first rapid transit system in the world, having begun operations in 1863.  More than 3 million passengers travel on the Underground every day, amounting to over 1 billion passenger journeys per year for the first time in 2006. The Underground has 11 lines, most of which connect the suburbs to Central London and together form a dense network in central London, linking major railway stations, central business areas and icons. The Underground serves North London much more extensively than South London. This is the result of a combination of unfavourable geology, historical competition from surface railways and the historical geography of London which was focused to the north of the River Thames. South London is served primarily by surface railways (the majority of London Underground's route length is actually on the surface rather than in tunnel.)
Carrying nearly 50% of London's commuters, the Tube is the most heavily used mode of public transport in the area.
Transport in London