Aerial view (of Terminal 5, from control tower) showing expanse of airport land with airliners at London Heathrow. Parked airliners are parked at the gates of Terminal 5 at this airport of five terminals on a site that covers 12.14 square kilometres (4.69 sq mi). London Heathrow is a major international airport, the busiest airport in the United Kingdom and the busiest airport in Europe by passenger traffic. It is also the third busiest airport in the world by total passenger traffic, handling more international passengers than any other airport around the globe.