If you have ever flown in or out of the United Kingdom, it is more than likely that you flew through one of London’s many airports in the process. If you are an international visitor from the United States or any other long-haul destination in the Western Hemisphere, Africa, Asia, or beyond, it is quite likely that you entered the country at either London Heathrow Airport (LHR) or London Gatwick Airport (LGW). If you are entering the UK from a European destination, it is far more likely that you will fly into the country from either London Stansted Airport (STN) or London Luton Airport (LTN), both of which are major hubs for the continent’s low-cost airlines.