The Natural History Museum is receiving a £5 million donation - the largest ever from an individual in its 133-year history.
The unprecedented sum of money is being given to the museum, which attracted 5.3 million visitors last year, by asset management firm founder and chief executive Sir Michael Hintze and his wife Lady Hintze.
The donation will be used to maintain collections and for scientific research behind the scenes at the London museum, which became the third most popular UK visitor attraction last year.
The museum said it had received seven-figure gifts and donations from individuals and corporate partners in the past, but nothing on this scale.
Philanthropist Sir Michael, the founder of asset management firm CQS, said: "Our gift recognises the museum's great value as a cultural and scientific institution, enjoyed by millions including ourselves.
"We feel privileged to be able to make a contribution towards securing this centre of scientific knowledge and research for present and future generations."
The museum is renaming a space which visitors enter at its Cromwell Road entrance Hintze Hall in honour of the donation, made through the Hintze Family Charitable Foundation.
Museum director Dr Michael Dixon said: "We are extremely grateful for this generous donation, which represents a big step towards ambitious plans for our future, for both our science and our galleries."
Culture Secretary Sajid Javid called the donation "incredibly generous".
He said: "Sir Michael has a long and most distinguished record of philanthropy, supporting culture and the arts alongside many other good causes.
"This donation, however, is extraordinary not simply in terms of its scale, but also as a truly magnificent example of philanthropic investment. It will have a real and lasting impact on the Natural History Museum."
The museum's origins date back to 1753, when Sir Hans Sloane left his extensive collection of curiosities to the nation.
It was housed in the newly-formed British Museum until Sir Richard Owen, who was in charge of the collection, persuaded the Government that a new building was needed.
The Waterhouse Building, in South Kensington, opened to the public on April 18, 1881.