The roots of the Potter films begin in 1997 with David Heyman, the man who has produced every installment of the series including "Fantastic Beasts." Heyman was looking for a young adult book series to pitch to the major studios, and received a copy of "Sorcerer's Stone" from his assistant. Two years later, Rowling sold the rights to her books to Warner Bros. for $2 million, on the condition that only British actors be cast.

One major exception to this was Dumbledore's original actor, the Irish-born Richard Harris. He repeatedly turned down the role because he did not want to commit to filming several sequels, but eventually relented for his Potter-loving granddaughter. Sadly, Harris passed away in 2002 after filming "Chamber of Secrets," and was replaced by Michael Gambon.

Part of the appeal of the Potter films has been watching Daniel Radcliffe, Emma Watson and Rupert Grint grow up with their characters, but that almost didn't happen. While looking for a director, WB considered Steven Spielberg, who wanted to do the films as an animated series that combined the books together. WB president Alan Horn vetoed the idea insisting the films be live-action.

Having only written four of the books at the time filming started, Rowling was brought on as a creative consultant to make sure the movie did not contradict her plans for the remainder of the series. To this end, she revealed plot elements she had not yet written to Alan Rickman, whom Rowling had hand-picked to play Snape. This included the reveal of Snape's love for Lily Evans from the climax of "Deathly Hallows."

Fans might remember protests against Pottermania from conservative Christian groups who claimed the franchise promoted pagan witchcraft. These had an impact on the filming of "Sorcerer's Stone," as requests to shoot at Canterbury Cathedral were blocked. Instead, the Dean of Gloucester welcomed the crew to film at his cathedral, saying that he was a big fan of the series.

Director Chris Columbus aimed to film as much of "Sorcerer's Stone" on-location as he could. While later films used more studio shooting, it was shot at major sites in England including King's Cross, Durham Cathedral and Alnwick Castle. The major exceptions were the Gryffindor common room and the Great Hall, which were filmed in-studio.

In both the books and the film, Platform 9 3/4 isn't really between platforms 9 and 10 at King's Cross. Platforms 9 and 10 are suburban platforms located in a rather mundane-looking part of the station, while the grander area seen in the film and depicted in the books is the inter-city area located on platforms 4 and 5. Still, if you go to King's Cross and find the real platform 10, you'll find nearby a sign for platform 9 3/4, featuring a luggage cart disappearing into the wall.

When casting for The Boy Who Lived, Columbus was bent on getting Daniel Radcliffe for the role after seeing him in the 1999 BBC adaptation of "David Copperfield." It almost didn't happen, though, as Radcliffe's parents were afraid that he would be overwhelmed by the media attention. After a long talk with Columbus and Heyman, they eventually agreed.

Rupert Grint's audition was completely different. To get the role of Ron Weasley, he sent in a videotape of him rapping about why he should be in the movie. In 2011, during a panel for "Deathly Hallows," he performed a part of his rap for a crowd of Potter fans.

Even today, the differences between Radcliffe and Grint are striking. While he's racked up over $95 million from his time playing Harry, Radcliffe admitted in a 2016 interview with The Telegraph that he's barely spent any of it. Grint, meanwhile, spent his money on fulfilling his childhood dream of owning an ice cream truck.

As for Emma Watson, she was reluctant at first to audition for Hermione, but was convinced to do so by her Oxford theatre teacher. She got the part after Heyman and Rowling were impressed by her confidence during screen tests.

In an attempt to remain as faithful to the books as possible, Watson was originally given fake teeth to match Hermione's buck-toothed smile from Rowling's descriptions. They were scrapped after Watson struggled to speak with them.

J.K. Rowling herself was offered a cameo in the film as Harry's mother, Lily, who appears in the Mirror of Erised. Rowling declined, and the role was given to Geraldine Somerville.

The floating candles in the Great Hall were created with a special effects rig that moved the candles up and down in special holders that created the illusion that they were floating. That rig was scrapped in the sequels after one of the wires snapped and dropped a candle. No one was injured, but it was decided that the candles would be entirely computer generated in later films.

While most movies are not filmed in chronological order, Columbus decided to film most of "Sorcerer's Stone" starting from the beginning to help Radcliffe, Watson and Grint come together as a group. One of the few exceptions to this was the Quidditch match, which was filmed last due to the high amounts of special and visual effects. Go to IMDb for more trivia, goofs and quotes.