Heathrow Terminal 5 is an airport terminal at Heathrow Airport, the main airport serving London. Opened in 2008, the main building in the complex is the largest free-standing structure in the United Kingdom. Terminal 5 is currently used exclusively as one of the three global hubs of International Airlines Group, served by British Airways and Iberia, with the others being London Gatwick South and Madrid Barajas Terminal 4. Prior to 2012, the terminal was used solely by British Airways.