Brighton Hippodrome has been named the most "at risk" theatre in the UK for the fifth consecutive year.
The Grade II-listed building in Middle Street is considered the "finest surviving example of its type" by the Theatres Trust.
Its future has been hanging in the balance since it closed in 2007, after 40 years as a bingo hall.
Comedian Dara O Briain appealed to local councils to view "at risk" venues as "opportunities" not "liabilities".
The 2018 list features 35 buildings across England, Scotland and Wales that the trust believes are most in danger of being lost.
The venues face a variety of threats including demolition, loss of funding, lack of maintenance or neighbouring development.
In second place on the list is the historic Theatre Royal in Margate, which dates back to 1787, and is one of the oldest surviving working theatres in Britain.
Helen Havercroft, head of growth and development at Thanet District Council, said: "I think this theatre is a viable theatre with a really rich future just like its past.
"Subject to funding, we've selected a partner, and we're hoping that that would allow for the refurbishment and renovation and a brand new start for the theatre."
Morecambe Winter Gardens in Lancashire, the Dudley Hippodrome in the West Midlands and the Victoria Theatre in Salford are also high on the list.
O Briain, a Theatres Trust trustee, said at the list's unveiling: "They are at risk of being lost forever, but they are also so achingly close to being saved."
He called on local authorities to "stop viewing these sites as liabilities and start thinking of them as opportunities".
In November 2017, Brighton's Hippodrome was sold by Academy Music Group to a private investor but the new owner's plans for the building are not yet known.
The theatre has hosted performers such as Dusty Springfield, Gerry and the Pacemakers and even Harry Houdini.
Brighton Hippodrome - journey through time
1897: The building starts life as an ice rink
1901: Architect Frank Matcham converts it to a circus
1902: It becomes a variety theatre
1965: The venue closes
1967: It reopens as a Bingo hall
2006: It closes again
David Fisher, director of Brighton Hippodrome Community Interest Group, said it was "disappointing" to top the list again.
He added: "It's very sad that Brighton should be in this position of not having a theatre of that size. It's really very frustrating."
Jon Morgan, director of Theatres Trust, added: "These venues are opportunities for local authorities to support and stimulate their local economy, provide a focus for local pride and act as an important community resource."
Brighton and Hove City Council has been contacted for comment.