Coloured dark blue on the map and running from Heathrow and Uxbridge to Cockfosters, the Piccadilly line is the fourth busiest line on the Underground network, receiving 210 million passengers per year.
And its popularity is no surprise, really, given that it serves many of London's top tourist attractions, including Harrods, Hyde Park, Buckingham Palace, Piccadilly Circus, Leicester Square and Covent Garden, as well as London Heathrow Airport, the busiest airport in Europe.
