Heathrow Terminal 5 was a massive construction project that was expected to cost £4.2 billion and take nearly a decade to complete. The new terminal was designed to be Europe's largest building site and airport terminal, housing all of British Airways' Heathrow operations and increasing Heathrow airport's overall passenger capacity by 30 million annually. However, the opening of Terminal 5 in 2008 faced significant issues that left many passengers unhappy with their experience.