It's hard to believe it's been ten years since "Iron Man" first hit theaters.

That blockbuster birthed an entire cinematic universe and paved the way for countless other Marvel characters to make their way to the big screen. To celebrate that anniversary (and the impending debut of "Avengers: Infinity War"), here are 14 interesting facts you might not know about "Iron Man."

1. "Iron Man" was trapped in development hell for nearly two decades before finally seeing the light of day. The film rights passed from Universal to Fox to New Line before ultimately reverting back to Marvel.

2.Quentin Tarantino was approached to direct "Iron Man" in 1999. Other potential directors included Joss Whedon and Nick Cassavetes.3. An early draft of the screenplay positioned Tony's own father Howard as the main villain, with Howard becoming War Machine in the film's climax.

4. Another early script featured a connection to Sam Raimi's "Spider-Man" trilogy, with Tony being revealed as the inventor of Doctor Octopus' robotic tentacles.5. Sam Rockwell was another top contender for the role of Tony Stark. While Robert Downey, Jr. eventually won the part, director Jon Favreau turned to Rockwell again to play Justin Hammer in "Iron Man 2."

6. "A Christmas Story" star Peter Billingsley was one of the producers on "Iron Man." He also has a small cameo role in the film as a scientist being yelled at by Obadiah Stane.7.Paul Bettany took on the role of J.A.R.V.I.S. as a favor to director Jon Favreau, and recorded all of his lines in about two hours. At the time, he wasn't aware of what film he was working on.

8. J.A.R.V.I.S., in the comics, stands for "Just A Rather Very Intelligent System." Fans of the TV series "Marvel's Agent Carter" would come to learn that the Stark family had an actual human butler named Jarvis.9. Filming began before the script was completed, and much of the dialogue was improvised on-set, often to the chagrin of studio executives.

10. One scene features Stane playing a piano piece by composer Antonio Salieri, whose rivalry with Mozart was made famous in the film "Amadeus." That musical choice was meant to subtly foreshadow Stane's betrayal of Tony.

11.Clark Gregg's Agent Coulson proved to be one of the breakout characters in "Iron Man," but originally the character had a much smaller role. At first he didn't even have a name -- just "Agent."

12. Near the end of the film, Tony can be seen reading a newspaper with a grainy photo of his Iron Man armor on the front page. That photo is actually taken from real-life paparazzi footage shot during production.

13. The three armors in the film were built by the legendary Stan Winston Studios. "Iron Man" proved to be the final film Winston worked on before his death in 2008.14. The post-credits scene featuring Samuel L. Jackson's Nick Fury was removed from preview cuts of the film in order to preserve the surprise.