On 31 May 1946, Heathrow Airport, 25 kilometres west of central London, was officially declared a passenger airport. It would soon surpass the scale of Croydon, which had been London's main airport until then.
During World War I, Heathrow served as an airfield, but was used for military purposes. In 1929, the first cargo terminal opened there, and in the 1930s it was used by Fairey Aviation as a testing ground for new equipment under the name Great Western Aerodrome.
In 1943, Heathrow became a base for the Royal British Air Force. Construction of the runways began in 1944 on land previously owned by the parish priest of Harmondsworth. The airport took its name from the village of Heath Row that was destroyed during the construction of the airport – around the site of today's Terminal 3.
The military did not need Heathrow and it was transferred to the Civil Aviation Authority. The first civilian flight out of Heathrow took place on 1 January 1946, a flight to Buenos Aires with a top-up in Lisbon. In 1947 three runways were completed at Heathrow and three more were under construction. The first runways were short and at different angles to the meridian in order to take the wind direction into account for take-off and landing.
In 2021, Heathrow will serve 67 million passengers annually, 11% of which are domestic flights, 43% are short-haul overseas flights and 46% are long-haul passengers. The busiest destination is New York. There are five passenger terminals and one cargo terminal. Heathrow is the seventh busiest airport in the world and the busiest in Europe.
Source:
Heathrow Airport official website