In this segment of Secrets of Underground London, learn about the history of the London Underground, also called the Tube. A London lawyer is first ridiculed because of his proposal to put a private railway below the city streets, and the initial building causes chaos. Using a cut-and-cover technique, streets were torn up and slums were demolished. The Underground was powered by steam, filling the tunnels with smoke. However, the new method of transportation was immensely popular, and the Underground system expanded rapidly. The clip also takes a look at how the map of the Tube was created to be exponentially more user friendly with a groundbreaking design.