Airports of London cannot be expanded due to the docks on either side. It is also the only airport serving London which does not operate at night. A light rail service from London City Airport DLR station, which adjoins the terminal building of London City Airport, links it to the financial district of the City of London at Bank and Monument stations, which offer interchanges with London Underground. Located in the London Borough of Hillingdon, Heathrow is by far the largest of London's airports and considered the main gateway into the United Kingdom for non-European visitors. Heathrow has four terminals and two parallel
London Underground in popular culture London Underground in popular culture The London Underground has long provided inspiration in various areas of popular culture. Filming is now managed all over the system but most commonly takes place at stations like Aldwych (a disused tube station), formerly on the Piccadilly line, or the non-operational Jubilee line complex in Charing Cross. The Waterloo & City line has occasionally been used for filming as it is closed on Sundays. The London Underground Film Office handles over 200 requests a month. Although not "filmed" as such on the Underground, there have been two animated children's television series set on and