Sergio Leone earned a place in film history with his Clint Eastwood-starring trilogy of Westerns (A Fistful of Dollars, For a Few Dollars More, and The Good, the Bad and the Ugly), and their follow-up, Once Upon a Time in the West. But the Italian maverick wasn't finished yet: He spent more than a decade trying to get his passion project made, a sprawling gangster epic called Once Upon a Time in America.

The final product, starring Robert De Niro and James Woods, captivated European audiences, but all American audiences got to see when it was released in 1984 was a butchered version that was barely half as long as Leone's cut. It wasn't until after the director's death in 1989 that his final movie came to be appreciated.

1. Sergio Leone turned down The Godfather to make it. 

By his own account, Once Upon a Time in America was Leone's pet project, the one he devoted most of his adult life to making. He became interested in the story while he was making 1968's Once Upon a Time in the West , and was so fixated on it that when Paramount approached him a few years later to make The Godfather, he politely declined. If he'd known it would take another 12 years to get Once Upon a Time in America produced anyway, maybe he would have accepted. But then where would Francis Ford Coppola be? 

2. Leone got (reluctant) input from the real Noodles. 

Once Upon a Time in America was based on The Hoods, a semi-autobiographical novel by Harry Grey (real name: Herschel Goldberg), who'd spent his youth engaged in some of the activities attributed to Noodles (Robert De Niro's character) and his gang. By 1968, when Leone approached him, Grey had no interest in meeting in person to discuss his work—after all, he was still in hiding from the gangsters he'd dealt with decades earlier—but was won over by the fact that he'd seen and enjoyed Leone's spaghetti Westerns. He agreed to meet for a drink, whereupon Leone peppered him with questions and Grey gave short, taciturn answers. It was this meeting that inspired Leone to tell the story the way he did: with an older Noodles looking back on his past, much as Grey did that night over drinks. 

3. Norman Mailer wrote one of the first drafts. 

The American author, then best known for his novel The Naked and the Dead and for his biography of Marilyn Monroe (the one that asserted she'd been killed by the FBI and CIA), took a stab at turning Leone's massive story outline into a coherent script. Leone was unimpressed. "I'm sorry to say, he only gave birth to a Mickey Mouse version," Leone later told American Film magazine. "Mailer, at least to my eyes, the eyes of an old fan, is not a writer for movies." 

4. Despite the title, not much of the film was shot in America. 

The bulk of the film was shot in Rome, at the famous Cinecittà Studios, where so many of Italy's best post-war movies were produced. Additional sequences were shot in such unlikely locales as Montreal, Paris, and St. Petersburg, Florida. 

5. The parts that were filmed in the U.S. were authentic. 

The 1920s Jewish neighborhood was a street in Williamsburg, Brooklyn that had been immaculately dressed to look just as it had 60 years earlier. The neighborhood was home to many real Hasidic Jews, some of whom would wander through the set in bemusement when the cameras weren't rolling. Leone was such a stickler for details that only the Hasids could tell who was real and who was an actor—and sometimes even they were fooled.

6. Brooke Shields almost played Deborah Gelly.

In 1981, the part that would eventually be played by Elizabeth McGovern was offered to 16-year-old Brooke Shields, whom Leone had seen in The Blue Lagoon and who he felt was ready for a more mature role. But a Hollywood writers' strike delayed the project, and Shields dropped out before anything came of it.

7. Robert De Niro almost dropped out of the film because Leone peed on his toilet seat.

Leone first approached De Niro about the film back in 1973, when his "pitch" basically consisted of him enthusiastically telling De Niro the story (through a translator; Leone never spoke English very well). De Niro was mildly interested, but he wasn't familiar with Leone's work ... and besides, it was only an idea at this stage, not a concrete project that he could sign up for. Years later, when the screenplay was finished, Leone again approached De Niro, who now eagerly accepted. But things went awry early in the process, when De Niro and producer Arnon Milchan met with Leone at his New York hotel suite, where a room was set aside for De Niro. The actor called the producer into his bathroom and said, "I can't do the movie." Why not? "Can't you see that he pissed all over my toilet seat?" Sure enough, there was pee on the seat. Milchan said surely it was unintentional, but De Niro was convinced it was a power play, like Leone was marking his territory. Milchan smoothed things over somehow, and De Niro eventually committed to the film. 

8. Nobody has ever seen Leone's complete version.

After the nine-month shoot, Leone had eight to 10 hours' worth of material. He trimmed it down to six hours, hoping to release it in two three-hour parts, but the producers were having none of that. So he reduced it to 269 minutes—four and a half hours—but it still wasn't enough. He chopped out another 40 minutes, and this 229-minute version is what premiered at the 1984 Cannes Film Festival and subsequently played in European theaters.

American distributors butchered the film even more, cutting out another 90 minutes and rearranging the scenes into chronological order (no more flashbacks), which rendered the movie incomprehensible. The American version flopped, of course, and Leone was devastated. A Martin Scorsese-led effort to restore Leone's original version resulted in a 251-minute cut playing at Cannes in 2012, but some 18 minutes were still missing due to legal issues over who owned the missing scenes. The 251-minute version is now available on Blu-ray and DVD. Someday, perhaps the complete version will be restored. 

9. It was Jennifer Connelly's first movie.

The actress who would later turn heads and earn awards for her roles in films like A Beautiful Mind and Requiem for a Dream was 12 years old when she was cast as the young ballerina-in-training Deborah. After a childhood career in modeling and TV commercials, it was the first real acting she had ever done. Jim Henson's Labyrinth came along shortly thereafter, and she's been a consistently busy (and in-demand) actress ever since. 

10. Even James Woods isn't sure what happened to his character.

At the end of the film, Max—now living as a politician named Bailey—asks Noodles to kill him. Noodles declines. But right after this, he sees a man who could be Max standing near a garbage truck, who then seems to disappear into the back of it, ground up with the trash. Was it Max? Was it someone else? Did it even really happen? Woods has no idea. He said Leone wanted there to be some ambiguity. To that end, the director used Woods' stand-in for the garbage truck scene—someone who resembled him from a distance but didn't necessarily have to be him.

11. De Niro's Method acting annoyed some people, including James Woods.

De Niro is a famously intense and thorough actor who truly "lives" in his roles. Woods, not so much. "It's just a bunch of old s***," he later said. "If it's a great script and you're working with good people, what's the problem? I'm tired of the Actors Studio bullshit that has ruined movies for 40 years. All these guys running around pretending they're turnips - they're so f****** annoying. It's 4 a.m. and you're trying to get some shot done and they're with a coach moaning about how they can't feel this, can't feel that. Just say the lines and get on with it!"

12. Leone was a perfectionist. 

Leone and De Niro had their different approaches, but one thing they had in common was perfectionism. According to one of the screenwriters, Leone did 35 takes of a large (and expensive) crowd scene, only to insist on one more because he noticed a kid in the crowd looking directly at the camera. 

13. The movie ruined Leone's health and contributed to his death.

The lengthy, arduous process of shooting a four-hour epic would take its toll on anyone, but especially someone who was already obese and in his 50s. The work exacerbated an existing heart condition in Leone, and the subsequent fight with distributors over the running time—plus his heartbreak over the film's failure in America—only made things worse. Leone died of a heart attack in 1989, before he was able to complete another film. Once Upon a Time in America, which had occupied so much of his career, proved to be his swan song. 

Additional sources:
De Niro: A Life, by Shawn Levy
Confidential: The Life of Secret Agent Turned Hollywood Tycoon Arnon Milchan, by Meir Doron and Joseph Gelman