A proposal to change the steps of the Philadelphia Museum of Art, made famous in the “Rocky” movie, is not definite, architect Frank Gehry said on Thursday.

Plans for a major expansion of the museum, unveiled to the media on Thursday, call for a 24-foot (7.3-meter) window in the center of the broad stairs seen in Sylvester Stallone’s Oscar-winning 1976 movie. In one of the film’s most memorable scenes, Stallone’s underdog boxer, Rocky Balboa, climbs the stairs as part of his training and exults upon reaching the top.

The window would connect to underground galleries to be designed by Gehry, known for dramatic, modernist designs, including the Guggenheim Museum Bilbao in Spain.

From inside, visitors would get a view of the Philadelphia skyline.

“We’re talking about a window to the city,” Gehry told reporters on Thursday. “It’s not a done deal. It’s something to talk about.”

Officials at the museum said they anticipate some public reaction to the proposal to change the 72 steps, which rank among the most popular tourist attractions in Philadelphia.

Visitors can often be seen re-enacting the “Rocky” scene, their arms raised in triumph.

The neoclassical museum building was completed in 1928.

Much of the expansion, which could take more than a decade, involves changes to interior spaces and excavation of portions of the hill where the museum stands to create underground galleries.

The plans could add as much as 169,000 square feet (15,700 square meters) of space and allow the museum to show off more of its collection of 230,000 objects, officials say.

Editing by Ellen Wulfhorst and Bill Trott.

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