Safety officials in Denbighshire have closed the Corwen Pavilion after concerns over asbestos.
Denbighshire council, which owns the site, said it took the step after a leak in a heating duct.
The described the move as a precautionary measure while investigations take place.
The pavilion is a popular venue for concerts and meetings, and hosted the first Urdd youth eisteddfod in the town in 1929.
The council said it had been forced to after the leak was discovered because the heating duct concerned may contain an asbestos seal.
All current bookings at the venue have been cancelled, and a strict "no entry" policy enforced at the building, until investigations are finished.
Denbighshire's head of leisure and youth service, Jamie Groves, said: "This is disappointing news.
"We have been actively working with the Corwen Pavilion Users Forum to try and find ways of improving facilities and looking at both short and longer term options for the site.
"We will keep Corwen residents informed of the situation as it progresses."
The council said safety laws on asbestos meant it had a duty to indentify any properties it owns that contain the substance, and to contain or remove it.
In a statement, council officials added: "Denbighshire has a management process for asbestos in place and we are working through this process in accordance with the regulations to limit the impact of the closure."