London Heathrow Airport opened for civilian commercial aviation on 31 May 1946, operating initially from military marquee tents along the Bath Road. It was known simply as London Airport until 1966, when the British Airports Authority renamed it Heathrow Airport to avoid confusion with Gatwick and Stansted. The site itself predates that opening by decades: Fairey Aviation had developed the land as a private aerodrome from 1929, and the British government requisitioned it in 1944, demolishing the hamlet of Heath Row to begin runway construction.

Located roughly 14 miles west of central London in the London Borough of Hillingdon, the airport is consistently Europe's busiest by passenger volume, handling 83.9 million passengers in 2024, and one of the most internationally connected hubs in the world. It is the primary base for British Airways and Virgin Atlantic. The original six-runway star layout was rationalised by the 1970s to just two parallel east-west runways, a constraint that still defines the airport's operational character and drives ongoing debate about a potential third runway.

The airport's physical layout is notably dispersed. Terminals 2 and 3 share a central zone between the two runways; Terminal 4 sits independently south of the southern runway; Terminal 5, opened in 2008 and home to British Airways and Iberia, anchors the western end of the site. In 1977, the extension of the London Underground's Piccadilly line made LHR the first capital city airport in the world directly accessible by metro. The Heathrow Express, launched in 1998, cut the journey to Paddington Station to 15 minutes. Beyond passengers, the airport handles over 1.5 million metric tonnes of cargo annually, making it the UK's largest port by value.