An Israeli shipping tycoon has donated £20m to the National Maritime Museum (NMM) in south-east London.
Sammy Ofer served in the Royal Navy in WWII
The gift from Sammy Ofer, who once served in the Royal Navy, will be used to help create a new wing at the world heritage site in Greenwich.
The £35m project, due to open in 2012, will be key to transforming the museum's exhibitions and collections.
Mr Ofer said the "hugely exciting" project would be "a great step forward for the museum".
The museum said the new wing would help drive its "strategic vision" to illustrate how "Britain's relationship with the sea has fundamentally shaped histories, cultures, economies, and identities across the globe".
It is hoped the project will enable the museum to engage with a new generation of audiences, both at the site and online.
The new wing will feature a substantial new space for special exhibitions, an open archive centre, new learning spaces, a new entrance, a restaurant, café and shop.
Mr Ofer served in the Royal Navy during World War II and the international shipping group he founded operates a significant part of its fleet from London.
Thanking Mr Ofer for his "extraordinary generosity" Lord Sterling, chairman of the NMM, said: "We are profoundly indebted to him for making such a far-sighted donation of his own personal wealth and in expressing such confidence in the future of the world's foremost maritime museum."
Work is due to start on the project later this year.