The London Underground was the first underground railway network in the world. It opened in 1863. Today, there are 270 stations and 400 km of tracks. There are 11 lines, each with a different colour. The London Underground is also known as the Tube because of its circular shape (it looks like a tube). Londoners use a travel card called “Oyster card” to take the Underground and buses, but sportier people don't use public transportation and get around by bike. Did you know that for two days, in October 2016, carriages drawn by unicorns replaced taxis in the streets of London? London is fun, isn't it?