00:00 The 19th century saw a population explosion in London, leading to transportation problems that were solved by the creation of the London Underground.

02:23 London's population explosion in the 19th century led to transportation problems, which were eventually solved by the creation of the London Underground.

04:24 The construction of the London Underground began in 1860 using the cut and cover method, and the Metropolitan Line, the world's first underground railway, opened in 1863 with 7 stations and quickly became popular despite the smoky conditions caused by the coal-burning steam locomotives.

06:36 The success of the Metropolitan Railway led to the expansion of the underground network, with new lines and stations being opened almost every year, and the construction of the Tower Subway in 1869 introduced a less invasive method of tunneling, allowing for deeper tunnels to be dug, although the problem of ventilation for smoke was not solved until the City in South London Railway opened the first deep tunnel that was electrified in 1890.

08:33 The formation of the Underground Electric Railway Company of London in 1902 led to the unification of the underground railways in London, and by 1933, all the railways had merged or been purchased by the company, resulting in the creation of a continuous single underground system known as the Public London Passenger Transport Board, which also included all-surface transportation, and the release of the famous tube map by Harry Beck.

10:34 During World War II, the London Underground served as an air raid shelter, with thousands of people seeking refuge in the deep tube stations, and several stations suffered direct hits resulting in casualties; after the war, the entire underground system was nationalized, and the first aluminum cars were introduced in 1952.

12:34 The London Underground is one of the most extensive subway systems in the world, with 11 lines, 272 stations, and over a billion passenger trips every year.