In a statement on Friday, the Prado said Foster would join Spain's Carlos Rubio for the project to refurbish the Hall of Realms.

The building, which until 2005 housed Spain's Army Museum, is the only surviving part of the Buen Retiro Palace, commissioned by King Felipe IV as a second residence. It was bought by the Prado last year, with the intention of increasing exhibition space.

Foster, who led the bidding team from his own firm Foster and Partners, said he was "honored" to contribute to this next phase of the expansion of the Prado.

Foster and Rubio's firms plan to open up the southern facade, and incorprate giant atrium to make the building appear semi-open, while keeping its original balconies.

"A new roof will harvest energy from integrated solar cells, give natural light to the galleries and cantilever as a shade to protect the southern facade," Foster and Partners said in a statement.

The Prado, widely considered to have the world's richest collection of pre-20th century masters, expects to finish the renovation in time for its 200th anniversary in 2019.

"This project has summoned up the memory of what the Hall of Realms was," said Mayor of Madrid Manuela Carmena. The museum said Foster and Rubio's proposal "respects and values what is already there, adjusting it to the necessities of our times."

Raised in Manchester, the 81-year-old Foster, is famed for his brand of "high tech architecture," with buildings that often reveal much about their inner structure to those looking from outside. Among the most celebrated of his creations is Hong Kong and Shanghai Bank HQ, the city of London's "gherkin," and the Reichstag dome in Berlin.

rc/jm (AFP, AP)