The first Rocky—which was released 40 years ago—told a seemingly improbable rags-to-riches story about a loan shark/amateur boxer going the full 15 rounds against a champion fighter that weirdly mirrored the improbable story of how the movie went from a distant dream of Sylvester Stallone’s to a real, Best Picture Oscar-winning film and subsequent franchise. On the 40th anniversary of the original film's release, here are some heavy-hitting, high-flying facts about the Rocky series.

1. STALLONE WROTE THE FIRST DRAFT OF ROCKY IN THREE AND A HALF DAYS.

With a little bit of screenwriting experience, and the idea for Rocky in his head for almost a year after witnessing a Muhammad Ali fight, Sylvester Stallone—who had $106 in the bank at the time—spent about 84 hours using a pad and a pen to write the first draft of Rocky. In his original version, Adrian was Jewish, Mickey was racist, the Paulie character was Adrian’s Jewish mother, Apollo Creed was Jamaican, and the script ended with Rocky throwing the fight and opening a pet store for Adrian with the money he made.

2. THE STUDIO WAS INTERESTED IN HAVING JAMES CAAN, BURT REYNOLDS, OR RYAN O’NEAL PLAY ROCKY.

United Artists offered Stallone up to $340,000 to sell them the rights to the screenplay if he agreed to not star in the movie. When the budget was lowered to $1 million, the studio was no longer allowed to keep Stallone from starring. He was paid $20,000 for the script and a SAG minimum of $350 per week for acting instead.

3. ADRIAN WAS ALMOST PLAYED BY SUSAN SARANDON.

Stallone and the producers decided that she was “too sexy." Cher was also considered. Bette Midler was offered the role but turned it down. Carrie Snodgress had in fact won the part, until her agent asked for too much money. Talia Shire auditioned at the last minute to save the day.

4. STALLONE AND CARL WEATHERS REHEARSED THEIR (FIRST) BIG FIGHT FOR FOUR WEEKS.

Director John G. Avildsen shot their rehearsals on Super 8 so that the actors could see what they were doing. When it came time for the actual pretend Creed/Balboa I, filmed at the Los Angeles Sports Arena, producers advertised that anyone who showed up to play the audience would receive a free chicken dinner.

5. ROCKY AND ADRIAN VISITED THE SKATING RINK AFTER IT WAS CLOSED FOR BUDGETARY REASONS.

Originally, Adrian and Rocky have a date during the skating rink’s operating hours. Because it would've cost money to pay for extras to skate around them, Avildsen asked Stallone to change the scene so that the couple had the rink all to themselves.

6. IT WAS A FAMILY AFFAIR FOR THE STALLONES.

Sly's brother, Frank Stallone Jr., played a street corner singer in Rocky, while Frank Sr. was the timekeeper for the fight. Stallone’s first wife, Sasha, received a kiss from Rocky during his training session in Rocky III.

7. CHARLIE CHAPLIN AND ELVIS PRESLEY WERE FANS OF THE FIRST MOVIE.

Chaplin wrote to Stallone that Rocky reminded the silent film star of a character he used to play. Stallone regretted turning down Chaplin’s invitation to visit him in Switzerland after the director died a few months later. Similarly, Stallone turned down Elvis’ offer to watch Rocky with him in Memphis months before The King passed away.

8. BURT YOUNG LOST WEIGHT FOR THE SEQUEL BECAUSE HE HADN'T PLANNED ON BEING IN IT.

He lost weight for another film; Young initially did not want to play Paulie again. Stallone wrote a line into Rocky II to address the obvious physical difference.

9. ROCKY’S FAMOUS RUN LASTED FOR 30.61 MILES.

Or his run in the sequel did, according to a 2013 calculation by Philadelphia magazine. Eight hundred Philadelphia children were used as extras for Rocky’s run from his house to the steps of the Philadelphia Museum of Art.

10. THERE WAS AN ALTERNATE ENDING TO ROCKY II.

Footage was shot of Adrian and Paulie actually witnessing Rocky and Apollo’s second fight in person, instead of back at home with the newborn baby. In that version, Adrian gets swept up into the ring with the other spectators and ends up in Rocky’s arms to end the movie.

11. THERE WAS A BIG DEBATE OVER THE ROCKY STATUE.

Stallone donated the 8’6”, 2000-pound statue of Rocky Balboa to the Philadelphia Museum of Art after filming of Rocky III concluded. Philly residents were divided on whether or not the statue deserved to remain at the top of the museum steps. The Art Commission eventually placed it on the sidewalk of the Philadelphia Spectrum sports arena. It briefly returned to the top of the steps in 1990 for Rocky V, then back to the Spectrum until 2006, when it traveled to the base of the Art Museum steps for its 30th anniversary, where it remains.

12. WYOMING AND CANADA PLAYED THE ROLE OF THE SOVIET UNION IN ROCKY IV.

The epic training Rocky went through before fighting Ivan Drago was shot in Jackson Hole, Wyoming. Camera, sound, and transportation equipment froze in the minus-20-degree weather. The Balboa/Drago match held in Drago’s U.S.S.R. was filmed at the PNE Agrodome in Vancouver, British Columbia.

13. DOLPH LUNDGREN SENT STALLONE TO THE HOSPITAL.

Lundgren hit Stallone so hard in the chest when shooting the first round of the Balboa/Drago fight that Stallone’s heart hit his breastbone and began to swell. Had he not been sent to the ER and then intensive care for eight days, the heart would have continued to swell until he died.

14. ROCKY WAS SUPPOSED TO DIE AT THE END OF ROCKY V.

Stallone cried writing the death of his iconic character. It was all for no reason, since two weeks into filming, Avildsen—who came back to direct Rocky V after Stallone directed parts II, III, and IV himself—was told by a studio executive that Rocky Balboa, like Batman, Superman, and James Bond, could never die. In the original script, Tommy "Machine" Gunn kills Balboa in their street fight, concluding with Adrian giving a heartfelt speech to the reporters crowded outside the hospital about how Rocky’s spirit will live on forever.

15. BOXERS JOE FRAZIER AND CHUCK WEPNER FELT THAT STALLONE TREATED THEM UNFAIRLY AFTER HEAVILY BORROWING FROM THEIR LIVES TO WRITE THE MOVIES.

Before Rocky Balboa did it, "Smokin'" Joe Frazier ran the steps of the Philadelphia Museum of Art and spent some early mornings punching meat at the slaughterhouse that employed him. He said in 2008 that he only received compensation for his Rocky walk-on cameo, and it was all a “sad story” for him. Stallone was initially inspired by watching Muhammad Ali fight a major underdog fighter named Chuck Wepner in 1975, who lost but managed to knock Ali down once in the match and became a local New Jersey hero. Wepner even wrestled Andre the Giant at Shea Stadium before Balboa battled the Hulk Hogan character Thunderlips in Rocky III. Wepner sued Stallone in 2003. The two settled for an undisclosed amount.

Ali, meanwhile, noted the similarities between himself and Apollo Creed. He didn’t seem to mind.

16. ROCKY’S TURTLES CUFF AND LINK OUTLIVED A COUPLE OF THE CHARACTERS.

The female red-eared sliders that appeared in 2006’s Rocky Balboa are the same turtles from the original 1976 picture.