The London Underground is one of the oldest, largest and longest metro systems in this planet, with its first section being established back in 1863. This entire system expands over the greater London, covering the regions of Buckinghamshire, Hertfordshire and Essex. More commonly known as the Tube, the Underground has 270 stations, spanning over 250 miles in length.

This subway transportation system is the busiest metro network of Europe after Paris and Moscow. The network withstands over 3 million journeys in a single day and recorded over 1 billion passengers in 2007. The Tube map itself, with its colour coding, has revolutionized various mapping systems across the globe.