The museum is in New York's Manhattan

The museum is undergoing a $600m (�366m) facelift and should be open again for its 75th anniversary in two years' time, its director Glenn Lowry said.

Its new galleries in Manhattan will feature column-free viewing areas for its modern works, glass curtain walls, a light-filled atrium 110 feet above street level and a restored sculpture garden.

The museum houses the biggest collection of modern art in the US, but moved to a temporary gallery across the city's East River last year when the rebuilding began.

Floor space is being almost doubled to 630,000 square feet, including almost 130,000 feet of viewing areas.

It will blend with its surroundings rather than stand out

And a new research and educational wing is also being built, although it will take at least a year or two longer than the rest of the building to be finished, said Mr Lowry.

The additions to the museum were designed by architect Yushio Taniguchi.

Speaking from Tokyo, he said he designed "a museum within a city - a city within a city", with the aim of integrating it into its location rather than attempting a radically distinctive design.

He said one of his key aims was to restore the Abby Aldrich Rockefeller Sculpture Garden to its original form.