London's Southbank Centre could be closed until at least April 2021 due to the impact of coronavirus.
The Southbank Centre which closed on 17 March is planning to cancel events from September to November.
It is forecasting a "best-case-scenario" loss of £5.1m for this financial year.
Chief executive Elaine Bedell said: "We're doing all we can to safeguard the Southbank Centre we currently know and love for the years ahead."
The centre has called for further government support, because the forecast included using up all its reserves, and £4m from the government's furlough scheme.
Its £19.2m annual grant from Arts Council England has been used "to effectively mothball the buildings".
The venue is considering the option of broadcasting concerts from behind closed doors through autumn and next spring.
Ms Bedell said: "We hope that we'll emerge from this crisis to a brighter future."
The Southbank Centre is made up of the Royal Festival Hall, the Queen Elizabeth Hall, the Purcell Room and the Hayward Gallery and offers more than 3,500 events a year.
It is also home to the National Poetry Library, the Arts Council Collection and eight orchestras including the London Philharmonic and the BBC Concert Orchestra.