Director Robert Zemeckis said he may not have made his new film The Walk had it not been for the events of 9/11.
He said that the 2001 terrorist attacks immortalised Philippe Petit's daring high-wire walk between the Twin Towers in August 1974 as "fable" that could never be repeated.
Asked if he would have made the film without the events of September 11, Zemeckis replied: "I don't know. I think that the towers were so tragically destroyed does a couple of things. One, it hurtles Philippe's adventure into almost a fable because it can never be repeated, obviously.
"But I also think that because the towers no longer exist, we're able to present a story that's very emotional and becomes a nice memory of them."
The Walk stars Joseph Gordon Levitt as Frenchman Petit who illegally walked a high-wire between the North and South towers of New York's World Trade Centre to the amazement of people watching below.
Zemeckis, 63, said he believed that one day the film might become part of the history of the towers.
"I think this is a film that portrays this wonderful, human moment in the history of the towers. (That moment) might even be the second most significant thing that happened to the towers so (this film) might become a historical document in the future."
The Forrest Gump director only discovered the story of the feat in 2003 in the children's book The Man Who Walked Between The Towers by Mordicai Gerstein.
He met Petit for the first time in 2006 and began to flesh out the story but plans for the movie were shelved by Disney. It eventually was offered a lifeline from TriStar and began production in January 2014.
Zemeckis said that he "very, very closely" identified with Petit's attitude to "stop at nothing" when he struggled to get the film off the ground.
"The idea that Philippe had this passion to express himself creatively and was going to stop at nothing to do it, I completely identify with that," he said.
The idea of his films being a "historical document" has made Zemeckis even more firm in his resolve not to remaster his classic Back To The Future triology, despite being a pioneer of cutting-edge digital techniques including performance capture.
"No, I think movies are historical documents and the way they were made when they were made is the way they should be kept and they shouldn't be tinkered with and that's my personal philosophy," he stated.
The Walk is out in cinemas on October 9.