Fare zone 1 is the central zone of Transport for London's zonal fare system used by the London Underground, London Overground, Docklands Light Railway[1] and National Rail.[2] For most tickets, travel through Zone 1 is more expensive than journeys of similar length not crossing this zone.[3] The zone contains all the central London districts, most of the major tourist attractions, the major rail terminals, the City of London, and the West End. It is about 6 miles (10 km) from west to east and 4 miles (6 km) from north to south, approximately 17 square miles (45 km2).[4]