Renowned architect Frank Gehry has proposed something that legions of movie fans consider heretical: changing the steps of the Philadelphia Museum of Art that were made famous by the movie “Rocky.”

The museum is about to begin a 10-year renovation. Most changes are inside: excavating beneath the east terrace and fountain, doubling exhibit space, filling it with light.

Gehry has also proposed adding a window, carved into the famous steps, so visitors inside the new exhibit space can orient themselves with the city outside.

Rocky runners, the legions who follow Sylvester Stallone’s famous path up the steps in “Rocky,” could still run up each side, but the sweep of the grand staircase would disappear.

It is merely a proposal, everyone at the museum stresses, and a decision on this last piece of the renovation is years away.

“Ten different ways it could go,” said Gehry. “Not a done deal yet. Something to talk about.”

But there already are plenty of people talking about it. The stairs have become a tourist attraction, both for those who just want to see the famous location and runners looking to re-create Rocky’s dash up the steps.

“I think it’s a real shame,” said Darren Brooks, of London, who had just run the steps and was enjoying the experience a second time by watching video of it on his wife’s phone. “You’ve got the view already. Right here. It’s magnificent.”

Mike Kunda, who runs tours culminating at the steps, isn’t happy about the proposal, either.

“The steps are a symbol of hope and inspiration,” he said. “Even though it’s corny, it is what it is.”

Museum officials said that they hope to make the building less intimidating.

“We need to improve the relationship of the museum with the city,” said Mark Rubenstein, a board member who chaired the master-plan review committee. “It’s a city museum, yet for some reason it’s blocked off from the city. The city can’t see in, and people who view art can’t see out.”

He described the museum as a “formidable institution,” one that “scares the hell out of people in the city. And we have to get over that.”

‘Magical area’

This is exactly how Stallone, who attended Philadelphia’s Lincoln High School, has said he felt when he wrote the screenplay to “Rocky” and created what has become the iconic scene of Rocky running the museum steps.

“The steps were like this magical area, like this intellectual bastion that I would only look at from afar,” Stallone wrote in the foreword to my book, “Rocky Stories: Tales of Love, Hope, and Happiness at America’s Most Famous Steps.” “It almost seemed like another city, like the Acropolis.”

Nobody involved in the original movie expected Rocky running the steps to become a ritual repeated by untold thousands. It just started happening. The Academy Award-winning movie will be 40 years old in 2016, and runners are as prolific as ever.

The steps are the heart of the Rocky world. Stallone came to understand this. He returns to them in “Rocky II.” A statue is erected in “Rocky III.” He runs them 30 years later, in the same gray sweatsuit, in “Rocky Balboa,” essentially Rocky IV.

Rocky’s transformation

Early in the first movie, an out-of-shape Rocky tries running the steps, but can’t make it all the way up. Near the end of the film, a morning before the championship fight, he runs to the top and lifts his arms in triumph.

He is celebrating his own transformation. He has regained his dignity and self-respect, and has realized that his success would have little meaning without the love of Adrian (played by Talia Shire) or friendship with Mick (Burgess Meredith).

In a similar fashion, many of the visitors who run the steps today are celebrating their own achievements or seeking motivation for challenges ahead. We met people who were the first in their family to graduate from college and came to run the steps, or who overcame cancer and came to run the steps, or who got their dream job and came to run the steps.

Some in the Rocky World fear that any alteration to the steps will ruin the experience so meaningful to so many.

David Brownlee, a University of Pennsylvania architectural historian, said that from a preservationist’s point of view — forget about Rocky for a moment — other elements of Gehry’s design may accomplish the museum’s mission without altering the steps. But he applauds the museum for being bold, for asking the question.

“I’m of two minds about this myself,” said museum CEO Timothy Rub, referring to the window. “But what’s been interesting to me is that, of the many people with whom we’ve shared the plan already, a good half of them are really excited about it. The other half say, ‘How can you even imagine messing with the steps?’

“It’s a matter of saying, ‘Here’s an idea. We’re thinking about it. What do you think?’ A museum should prompt these conversations,” Rub said.