Which London Underground line provides the Tube service to Heathrow Airport?

The Piccadilly line provides London Underground’s Tube service to Heathrow Airport.

The line serves Heathrow’s terminals through stations at Heathrow Terminals 2 & 3, Heathrow Terminal 4, and Heathrow Terminal 5. Trains to Terminal 4 and Terminal 5 use different branches, so passengers need to check the destination shown on the train or platform display.

The Piccadilly line opened in stages from 1906, originally linking Hammersmith with Finsbury Park. Its western extension reached Hounslow and Uxbridge, while the route to Heathrow opened later. Heathrow Central station, now called Heathrow Terminals 2 & 3, opened in 1975; Terminal 4 followed in 1986 and Terminal 5 in 2008.

The Elizabeth line and Heathrow Express also serve the airport, but they are not London Underground services. The Piccadilly line remains the classic Tube route connecting central London with Heathrow, although the Elizabeth line provides another rail option.