<P> Located only four miles from Canary Wharf, London City Airport is often used by business travellers, with many flights serving destinations across the UK and northern Europe . The airport cannot be expanded due to the docks on either side . It is also the only airport serving London which does not operate at night . </P> <P> 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 . </P> <P> 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 runways . Due to the location in London's western suburbs, Heathrow has had trouble trying to expand, with various expansion projects being cancelled .) As a result, the airport consistently runs at over 99% capacity and is often included on lists of the worst - rated airports in the world . However, on 1 July 2015 Heathrow's expansion plan was suggested as the best option by the Airport Commission and on 25 October 2016 a new northwest runway and terminal was approved by the Government . </P> <P> The airport is connected to Great Britain's motorway network via the M4 and M25 motorways, to London Paddington station by Heathrow Express and TfL Rail trains and to other Central London destinations by London Underground trains on the Piccadilly line . </P>

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