London has one of the most comprehensive public transport systems in the world. London Underground - also known popularly as The Tube - has trains that criss-cross London in the largest underground rail network anywhere in the world. And, despite residents’ constant, and sometimes justified, grumbling about unreliability, public transport is often the best option for getting anywhere in the city. The Tube is made up of 11 lines each bearing a traditional name and a standard colour on the Tube map. Visitors should be aware, however, that the Tube map is actually a diagram and not a scaled map, making it misleading for determining the relative distance between stations.