On November 16, Harry Potter and the Sorcerer's Stone is celebrating its 20th anniversary. The film, directed by Chris Columbus and based on the book series by J.K. Rowling, launched the careers of then child stars Daniel Radcliffe, Emma Watson, and Rupert Grint. The film was incredibly successful due to the casting of these young actors alongside talented British luminaries and its faithful adaptation of the beloved book series.

Related: Who Played Voldemort In Sorcerer's Stone (& Why They Were Changed)

Columbus spoke with Screen Rant about celebrating the 20th anniversary, working with John Williams on the film's iconic score, and learning secrets from Rowling.

Screen Rant: Like so many of your films, Harry Potter evokes a certain emotion for me, and I think a lot of people. What does it feel like for you to watch the film when it comes on and look back on it 20 years later?

Chris Columbus: You know, I have not seen the entire film screened since I went to opening day back when it came out. I've seen it a billion times on television, but I'll always watch one scene and I'll say to myself, "Oh I should have done this. I should have done this." And then I'll turn it to a different station.

It's just remarkable to me because [when] we designed the film, our mantra for the crew was, "Let's make something timeless. Let's make something that, when people are watching this 15 - 20 years from now, it feels as if it might have been made yesterday." Now, obviously, visual effects have come a little further. So there are certain things that can't make it completely timeless, but I think that's part of it.

I wanted audiences who watch it on television to say, "Wait. What year was this shot? Was it 1956? Was it 1984?" I wanted that sort of confusion, in a good way. I see The Wizard of Oz and, I'm not comparing it to The Wizard of Oz, but I'm saying, I get that sense from The Wizard of Oz, "What year was this?"

And I think there's a lot of elements that make it feel that way. One being John Williams, and I have to know when you first heard Hedwig's Theme, did you pass out? What was your reaction?

Chris Columbus: I was fortunate enough to work with John on Home Alone. So when I heard that theme, I almost passed out. But when I heard the Potter theme, John played it for me on the piano. He just plunked out [hums Harry Potter Theme]. And I thought, "This is the guy." I always knew it was the guy who did Raiders, and Star Wars, and ET and Jaws. But he's done another iconic thing and I'm the recipient. It's one of those great geek moments for a guy who loves movies. I was like, "Oh my God. I can't imagine what the rest of the score is gonna be like." And then, the rest of the score was equally astounding.

I was watching the movie last night and one of my favorite things is at the end when Dumbledore tells Slytherin in front of them that they won the House Cup. And then he’s like, "You guys won….second Place because I’m giving points to Gryffindor!" I think that's so funny.

Chris Columbus: By the way, it's inherent to who Richard Harris was, even though it was written that way in the book, that's who Richard Harris was. I mean, he was the ultimate prankster. That's why his Dumbledore, to me, is so great, because it's something he would have done. Richard had this devilish look in his eyes. You never knew what he was going to say or do and he was capable of outrageous behavior.

There are some somewhat infamous trivia facts about this movie that I would love to hear your anecdotes on. One is that J.K. Rowling told Alan Rickman these vital details regarding Snape's arc in the future books and things that helped him craft this character. I was curious if there was anything revealed to you about future stories that you were able to incorporate in the first two Harry Potter films?

Chris Columbus: No, I mean, the Snape situation happened at dinner, I think. Alan learned all this information and he's sworn to secrecy. So he couldn't even tell. You'd think [J.K. Rowling] may have told the director, but I guess he needed to know. And it really didn't affect anything in terms of what I had to do.

Except, in certain scenes, Alan would do these little idiosyncratic things with his acting. I'd ask him after the take, "Why did you choose to do that?" He'd say, "You'll know after you read book seven." But I was like, "Well, that's a few years down the road." But I loved what he was doing, even though I didn't know why, and I kept it in the movie. And then finally, when I did read book seven, a light bulb went off, and I said, "That's why he did that." So, that was great.

We learned little things here and there. The biggest thing we needed to know because there were only three books, was how dark the series was going to get. That was Jo Rowling's intention from the beginning. We knew we were designing Film One as almost this storybook, 'Welcome to Hogwarts' with a little bit of darkness. But we knew that when we got to Chamber of Secrets, it was going to get darker, Azkaban was going to get darker. So, that was the design of the films from day one.

The whole cast has just glowed up, it’s incredible watching them. What is it like for you, seeing these kids that you knew when they were so young and what they’re doing now?

Chris Columbus: Having done Home Alone with Macaulay Culkin, who had only done one small part in a film prior to that, I realized you get this real naturalistic, honest quality. You don't have a kid who's done 17 years of Nickelodeon TV shows, you've got someone who's bringing some naturalistic, realistic performance to the set. That's why we cast Dan, Rupert, and Emma, and, quite frankly, all the other kids as well. They brought a freshness to the franchise, which we didn't know was going to be a franchise at the time.

But, it also was fraught with a lot of chaos. Because the first months of the movie, these kids were just so happy to be in a Harry Potter movie, on a Harry Potter set, dressed as these characters, that they would say a line, look into the camera and smile, wave, look to each other like, "Even though it's not part of the scene, can you believe we're here?" So, it became an exercise for me. Suddenly, I became an acting teacher, which by the way, is what a director has to do anyway. But this was pure, full-on Acting 101. By the time we got to the middle of the second movie, the kids had grown into really strong actors. And that just continued to happen over the years. As you can see in the films, they all became great actors.

Harry Potter and the Sorcerer's Stone Daniel Radcliffe Rupert Grint Ron Weasley

I don't know if this is true, I read that you had passed on directing Spider-Man to direct Harry Potter, is that true? 

Chris Columbus: Yeah

That's like a wild thing to me because that is a butterfly effect of two major franchises - there's an alternate universe here.

Chris Columbus: It is weird, because, you know, I'm of the firm belief that every movie ever made would be better with Spider-Man in it. There's no question. So I mean, how good would The Godfather be if Spider-Man showed up?

But honestly, the reason I got into the film business, the reason I got into movies as a kid, was because of Marvel Comics, because that's what I wanted to do. And Spider-Man was my hero as a kid. I really probably heard the day before I got the Spider-Man offer, that I got Harry Potter. And whoever it was, was like, "Is he crazy? How could he pass up Spider-Man?" and part of me felt that way because it's probably something I was waiting my entire life to do. But I'm glad I decided to go with Potter. I'm happy about that.

What if that opportunity came up again?

Chris Columbus: I think it's been done really well. You don't need me to do Spider-Man.

Next: Harry Potter/Fantastic Beasts Official Timeline