London mayor Boris Johnson has got his hands dirty digging the first pile of earth at the launch of the Tate Modern’s massive £215M expansion.
The development will ease the strain on the beleaguered building, which pulls in five million visitors a year - three million more than it was designed for.
Tate Modern said it welcomed more than twice the number of visitors as MoMA in New York or the Pompidou Centre in Paris, but it has around half the available space.
The plans should increase the available space by 60%.
Demolition work will also begin soon to clear the area south of Tate Modern and open up a new route from the Millennium Bridge through the building to Southwark.
Sporting a hard hat and workman’s jacket, Mr Johnson joined Tate director Sir Nicholas Serota, and hailed the development as leading regeneration in the area.
He said: ‘This is the beginning of a fantastic new project… Many of the great buildings in the world have been fusions of architectural styles.’
Tate Modern occupies the former site of Bankside Power Station, designed by Giles Gilbert Scott and decommissioned in the early 1980s.
It was converted by architects Herzog & de Meuron, who are creating the new development, which was granted planning permission in March 2009.
Planners have always envisaged that Tate Modern would be transformed in two phases, with the second phase bringing the derelict oil tanks and power station switch house into public use.
Once the switch house is opened up, visitors will be able to cross the river Thames, walk through the existing Tate Modern and Turbine Hall and out onto a new plaza, which will feature paths drawing people into the heart of Southwark.
The project is due to be completed in 2012 at an estimated cost of £215M. Tate has so far raised £76.5M - around a third of the overall costs.