LOS ANGELES — The long-delayed Academy Museum of Motion Pictures will open on Dec. 14, completing a nine-decade quest by the Hollywood establishment to celebrate itself year-round.

Tom Hanks announced the opening date during the 92nd Academy Awards on Sunday night. “It’s going to be a very big deal,” he said. “We’ll see you there.”

The museum was initially scheduled to open in 2017 and cost $250 million. Setbacks have included sparring architects, a ballooning budget (now at least $388 million), construction difficulties and the forced departure of the institution’s inaugural director, Kerry Brougher, last summer.