The Heritage Lottery Fund has announced funding of £2.5 million towards the National Theatre's £70 million redevelopment project.
"We are delighted the Heritage Lottery Fund has made this generous grant, which is a welcome vote of confidence in our plans to conserve and renew Denys Lasdun's 1970s building," said chief operating officer Lisa Burger.
"The pre-eminent example in Britain of mid-twentieth century modernism, it gained grade II• listed status in 1994.
"The theatre now requires significant investment in the fabric of its building; HLF's funding will enable us to create increased public access to the architectural, theatrical and social history of the National Theatre."
Dame Jenny Abramsky, chair of the Heritage Lottery Fund, said: "The National Theatre is one of the South Bank's most recognisable landmarks which we're delighted to be supporting as it approaches its 50th anniversary.
"Along with much-needed redevelopment work, imaginative plans to engage visitors with all aspects of this world-class theatre and its archive collection are something we warmly welcome."
We reported last week on the opening of The Shed, a temporary theatre next to Waterloo Bridge, which will provide the National with a third stage during the extended closure of the Cottesloe Theatre.
For the latest local news and events direct to your inbox every Monday, you need our weekly email newsletter SE1 Direct.