A ceremony marking a major milestone in the huge Terminal 5 development at Heathrow Airport has been held.
The terminal earlier in the construction process
The transport secretary and airport operator BAA's chief executive laid a concrete slab in the departure lounge.
Said to be Europe's largest building site, T5 is the size of Hyde Park. The departure lounge has now reached full height and will partially open in 2008.
It will serve an extra 30m passengers a year. Environmentalists say it will mean more air travel and pollution.
Transport secretary, Alistair Darling, said the government had to deal with "the genuine environmental concerns that people have".
But he said Heathrow provided tens of thousands of jobs, adding: "Terminal 5 will provide Heathrow with a new world-class terminal - a spectacular first impression for passengers arriving at the airport.
"The government is determined to do all that it can to ensure Heathrow's important position in the world."
Work started in 2002 and the second phase of the terminal is scheduled to open in 2011.
Construction of Terminal 5 began after a record public inquiry following opposition from local people and environmentalists.
The main building is 400m by 180m and will contain 105 lifts, 65 escalators and will consist of 80,000 tonnes of steel.
The managing director of Terminal 5, Tony Douglas, told BBC London: "You could fit 52 full-sized football pitches in its floor plates, it's the largest free-standing building in the whole of the UK."
People living near by say they fear a sixth terminal could be built.