Twenty years ago, fans young and old lined up at theaters to watch the very first Harry Potter movie, "Harry Potter and the Sorcerer’s Stone.” The film was the first moving in the eight-part film franchise based on the international best-selling books by J.K. Rowling.

Christopher Columbus directed two films in the franchise and looks back at the first movie that made more than a billion dollars. Columbus said the film holds up today, 20 years later.

“That was the goal with Potter. We wanted the film to sort of feel as relevant as it did the day it was made. If you look at the film now, it feels as if it could have been made yesterday,” said Columbus.

The film introduced three young actors to the world, but it took extra work and a little luck to cast the main character, Harry Potter.

“I think we were very fortunate in terms of getting the right cast,” said Columbus. "You know, it was difficult to get Dan Radcliffe initially because he didn't want to, you know, his parents did not want him to be exposed to what was eventually going to happen in terms of fame, and exposure. We wanted him. I had seen him and David Copperfield and our casting director said it's never gonna happen. His parents did not want him to do this role. And our producer David Heyman was at the theater a few weeks later, and Dan and his father were sitting a few seats away. And David approached him at intermission and convinced them to come in for the audition. That's, that's a very fortunate piece of the filmmaking Gods looking down on you, in a good way.”

Columbus reminisced about getting the job and working with J.K. Rowling.

“When I finally got the job, I thought, This is great. I've got the job that lasted about five seconds,” Columbus said. “And then it was filled with terror and anxiety. And they said, Oh, you've got one more thing to do, is you have to go to Scotland and meet Jo Rowling. And I flew to Scotland. And she said to me, so how do you see this film, then I just sort of spoke for about two and a half hours non stop. You know, I was just telling her my vision for the film. And after that meeting, she said, I see it exactly the same way. So that was a vote of confidence that, you know, kind of got me through the entire shooting is the fact that she had my back.”

Columbus said there were secrets on the set saying Alan Rickman, who plays the character Snape, went above and beyond to create that performance.

“The biggest secret was when Alan, and it's not a secret, I've told a couple of people. But when Alan Rickman got the role, he had a dinner with Jo Rowling, and she basically told him where Snape’s character was going throughout the books, and told him about book seven. So he had these weird idiosyncrasies on the set when we were shooting. And I would ask him, Why are you doing this particular thing? And he said, You'll know when you read books seven, so I was like, Well, I guess I'll accept it,” said Columbus. "To me saying I think his performance was brilliant. And then finally, when I read book seven, I realized that's what he was doing.”

As with most directors, Columbus said if he could go back and change something about the film he would.

“I would like to spend another few months working on the visual effects of the Quidditch match,” said Columbus. “Because I see certain things I could have done better, a little more exciting, but it's like that with every film. You know, it's why you shouldn't watch your films.”

The eight Harry Potter films earned nearly $8 billion worldwide, making it one of the most successful franchises in movie history.