Norfolk Museums Service has secured £9.2 million from the Heritage Lottery Fund for the Norwich Castle: Gateway to Medieval England project.
This announcement includes an initial development grant of £462,400 approved by HLF in May 2016.
This latest major grant, combined with £3.6 million raised from other public and private sources, will enable the multimillion-pound plan to transform Norwich Castle’s keep to go ahead, subject to formal planning consent.
The castle expects the redevelopment will mean it can attract an extra 100,000 visits a year, bringing its total to more than 300,000 visits annually, enhancing Norwich’s profile regionally and internationally as a major cultural tourism destination.
Building work should start in summer 2019 and the transformed keep is due to re-open in 2020.
Ros Kerslake, chief executive of HLF, said: “This major project is set to transform Norwich Castle, bringing it back to life in a way that recognises the important role it once played as one of the most important buildings in Europe and making a real difference to the region’s heritage and tourism offer.”
Councillor Alan Waters, leader of Norwich City Council, added: “Norwich Castle has long been a cultural jewel in our fine city and one which deserves to be better known.
“This wonderful news will ensure that many hundreds of thousands more visitors will be able to explore and understand one of Europe’s most important 12th century secular buildings in greater depth than ever before.”