London

===Aviation===
{{main|Airports of London}}
[[File:Heathrow Terminal 5C Iwelumo-1.jpg|thumb|[[Heathrow Airport]] is the busiest airport in Europe as well as the second busiest in the world for international passenger traffic ([[Heathrow Terminal 5|Terminal 5]]C is pictured).]]
London is a major international air transport hub with the [[World's busiest city airport systems by passenger traffic|busiest city airspace in the world]].<ref name="Busiest skies"/> Eight airports use the word ''London'' in their name, but most traffic passes through six of these. Additionally, [[Airports of London|various other airports]] also serve London, catering primarily to [[general aviation]] flights.
*[[Heathrow Airport]], in [[London Borough of Hillingdon|Hillingdon]], West London, was for many years the [[World's busiest airport|busiest airport in the world]] for international traffic, and is the major hub of the nation's flag carrier, [[British Airways]].<ref name="london_135">{{Cite web|year=2020|title=Heathrow Airport Travel Report 2019|url=https://www.heathrow.com/content/dam/heathrow/web/common/documents/company/heathrow-2-0-sustainability/futher-reading/Heathrow-Airport-Travel-Report-2019.pdf|access-date=25 March 2021|website=[[Heathrow Airport]]|publisher=LHR Airports Limited|page=38}}</ref> In March 2008 its fifth terminal was opened.<ref name=london_137>{{cite web |url=http://www.heathrow-airport-uk.info/heathrow-airport-terminal-5.htm |title=Heathrow Airport Terminal 5 |publisher=TMC Ltd |access-date=27 April 2008 |archive-url=https://web.archive.org/web/20110430195211/http://www.heathrow-airport-uk.info/heathrow-airport-terminal-5.htm |archive-date=30 April 2011 |url-status=dead }}</ref>
*[[Gatwick Airport]], south of London in [[West Sussex]], handles flights to more destinations than any other UK airport and is the main base of [[easyJet]], the UK's largest airline by number of passengers.<ref>{{cite web|title=Airline Data Annual Reports 2017|url=https://www.caa.co.uk/Data-and-analysis/UK-aviation-market/Airlines/Datasets/UK-Airline-data/2017/Airline-data-annual-reports-2017/|access-date=25 March 2021|website=[[Civil Aviation Authority]]}}</ref>
*[[London Stansted Airport]], north-east of London in [[Essex]], has flights that serve the greatest number of European destinations of any UK airport and is the main base of [[Ryanair]], the world's largest international airline by number of international passengers.<ref>{{cite web |url=http://www.stanstedairport.com/about-us/london-stansted-airport-and-mag/facts-and-figures/ |title=Facts and Figures – Stansted Airport |website=stanstedairport.com}}</ref>
*[[Luton Airport]], to the north of London in [[Bedfordshire]], is used by several budget airlines (especially easyJet and [[Wizz Air]]) for short-haul flights.<ref>{{cite book |url=http://www.london-luton.co.uk/en/ |title=London Luton Airport |year=1969 |publisher=London Luton Airport |access-date=27 April 2008 |isbn=978-0-11-510256-1 |archive-url=https://web.archive.org/web/20110501023741/http://www.london-luton.co.uk/en |archive-date=1 May 2011 |url-status=dead}}</ref>
*[[London City Airport]], the most central airport and the one with the shortest runway, in [[London Borough of Newham|Newham]], East London, is focused on business travellers, with a mixture of full-service short-haul scheduled flights and considerable [[business jet]] traffic.<ref>{{cite web |url=http://www.londoncityairport.com/Default.aspx |title=London City Airport&nbsp;— Corporate Information |publisher=London City Airport Ltd. |access-date=6 June 2008 |archive-url=https://web.archive.org/web/20110423115236/http://www.londoncityairport.com/Default.aspx |archive-date=23 April 2011 |url-status=dead }}</ref>
*[[London Southend Airport]], east of London in [[Essex]], is a smaller, regional airport that caters for short-haul flights on a limited, though growing, number of airlines.<ref>{{cite web |title=Londoners love our airport |date=18 May 2018 |first=Adam |last=Cornell |url-status=live |url=http://www.echo-news.co.uk/news/16234556.Londoners_love_our_airport/?ref=rss |archive-url=https://web.archive.org/web/20190612091241/http://www.echo-news.co.uk/news/16234556.Londoners_love_our_airport/?ref=rss |archive-date=12 June 2019 |access-date=8 August 2019}}</ref> In 2017, international passengers made up over 95% of the total at Southend, the highest proportion of any London airport.<ref>{{Cite web |year=2017 |title=Airport data 2017 – UK Civil Aviation Authority |url=http://www.caa.co.uk/Data-and-analysis/UK-aviation-market/Airports/Datasets/UK-Airport-data/Airport-data-2017/ |url-status=live |archive-url=https://web.archive.org/web/20210226130311/https://www.caa.co.uk/Data-and-analysis/UK-aviation-market/Airports/Datasets/UK-Airport-data/Airport-data-2017/ |archive-date=26 February 2021 |access-date=25 March 2021 |website=[[Civil Aviation Authority]]}}</ref>