 -- October 4, 1990 was a special day in pop culture history. After all, that was the day "Beverly Hills, 90210" premiered.

"The show was on for a while, and it was O.K. the ratings," Jennie Garth once told The New York Times of the early days. "Then we filmed all of our risqué summer episodes at the beach and aired those at the time when the other shows were in reruns. So we caught a huge teen audience, kids that were home from school. And then it just went crazy."

By the time the show ended in 2000, ratings had dropped, but still, more than 8 million viewers were regularly tuning in.

Still, here are 25 facts that even the most die-hard fan of the series might not know.

1. The cast changed throughout the series, though Jennie Garth, Tori Spelling, Brian Austin Green and Ian Ziering stayed on for the show's 10-year run. (Jason Priestley left after season 9.)

2. Of all of Aaron Spelling's shows, "90210" enjoyed the longest run.

3. Gabrielle Carteris left the show after season five to launch her own talk show, which lasted for one season.

4. Tori Spelling claimed in 2000 that her famous father didn't tell her about the series -- her agent did. She auditioned under a different name, but told Entertainment Weekly in 2000, "I'm sure [getting the part] had something to do with my dad."

5. Jennie Garth told People magazine in 1992 that she and Shannen Doherty fought "like cats and dogs" for some time, but by then, she'd learned to get along.

6. Shannen Doherty made other enemies on set too. Aaron Spelling told Entertainment Weekly in 2000 that her tardiness on set "upset the cast members tremendously." "I remember them calling me and saying, 'Please, can’t you get her here on time?' he recalled. "[But] it wasn't like she ruined the show or anything."

7. Tori Spelling put off going to college for the show. "Every year I was like, 'It probably won’t go another year. I was going to go to USC, so I deferred a year,'" she told Entertainment Weekly. "Then the show went again. It was like, 'I’ll go when I’m done.' Now it’s 10 years later and I’m 26." Spelling never did earn a college degree.

8. It's been reported that originally, Tori Spelling's character's name was "Donna Morgan." It was later changed to "Donna Martin."

9. The high school featured in "Beverly Hills, 90210" was Torrance High School in Torrance, California. It was also featured in "Buffy the Vampire Slayer."

10. According to Jason Priesley, several members of the cast had romantic relationships with each other. "Various combinations of people slept with each other over the years," he wrote in his memoir, according to the Hollywood Reporter. His first "full-fledged adult relationship," he added, was with Christine Elise, who played Emily Valentine on the series.

11. Jennie Garth said in a "Watch What Happens Live" interview that Jason Priesley partied harder than Shannen Doherty.

12. Of all of her character's trials and tribulations, Jennie Garth told Andy Cohen that she thought Kelly getting amnesia was more of a jump-the-shark moment than when she joined a cult.

13. Jason Priesley told The New York Times that he was the last person cast -- and it happened at the eleventh hour. "I read for Aaron on Thursday. I got the job Friday afternoon, and on Monday we started production," he said.

14. Creator Darren Star told The New York Times that the local affiliates were "scandalized" by the episode in which Shannen Doherty's Brenda and Luke Perry's Dylan had sex on prom night because Brenda wasn't upset about it. "I was strongly advised to write a show that would address the consequences of that sexual experience," he said. "So the first episode of the second season Brenda broke up with Dylan because their relationship had gotten too mature."

15. Jason Priesley left the show in the middle of the ninth season on bad terms. "I did the first scene of the morning – literally with this actor who was brought in to replace me – and that was it. I hugged the crew, picked up my box of stuff, went to my car and drove away," he told the Guardian. "There was no party, no nothing. I felt like I'd wasted nine years of my life."

16. Before getting cast as heartthrob Dylan McKay, Luke Perry was laying asphalt, creating parking lots. "The show has changed my life immeasurably. Life is certainly never gonna be the same," he said in a 1993 interview. "It has been good for the most part. I mean, it certainly has some drawbacks, but I'm not bitching."

17. The wardrobe department would try to find "ridiculous" material to make clothing for the stars to wear on the show, Brian Austin Green told Details magazine. As a result, his character, David Silver, once appeared on screen wearing a pair of pants with Lifesavers on them. "I wore clothing that looked like outdoor f***ing umbrella material," he said.

18. Gabrielle Cateris told Access Hollywood that when she auditioned for the part of teenager Andrea Zuckerman, she lied about her actual age -- 29 -- to appear younger. “I actually talked to a lawyer about how could I sign these contracts and lie about my age and still be able to do the show. Is it OK?" she said. "[The lawyer said] ‘Yes it is, as long as you just say you’re over 21.'"

19. Tiffani Thiessen, who joined the show in season 5, told Meredith Vieria that her first on-screen kiss was not with her then-real-life boyfriend, Brian Austin Green, but with Luke Perry. "That was probably the more awkward thing," she said. "Literally having your boyfriend on the show and then literally kissing another man, 'I get paid for this, honey. I don't know what to tell you.'"

20. The show spawned seven specials, including a 2003 retrospective called "Beverly Hills, 90210: 10 Year High School Reunion" that featured all the primary original cast members. It was the first time Shannen Doherty reunited with her former castmates in nine years.

21. Tiffani Thiessen was great for ratings. Her first episode as bad girl Valerie Malone was one of the show's most popular episodes.

22. The show was nominated for one Emmy throughout its run -- Milton Berle, who had a guest role.

23. Jennie Garth said that Ian Ziering tricked her into rehearsing a kissing scene. "He was wise and ambitious as hell. I remember that we had to kiss in one of the earlier episodes, like right after we had met, and he asked if we could go to the garage of this house we were shooting at 'to rehearse'" E! News reported that she wrote in her memoir. "Of course, I know now that you don't have to ‘rehearse' those kisses... I told you he was ambitious!"

24. When Ian Ziering first got the script for the series, he thought, "Boy, this is very superficial," he said. "The pilot was all about the glitz and the glamour of Beverly Hills, the obnoxious kids, and the fish-out-of-water story of Brenda and Brandon Walsh," he told Entertainment Weekly. "I couldn’t discern from that first script that the show would become very issue-oriented."

25. Luke Perry believes that Jason Priesley's Brandon Walsh would be a better match for Jennie Garth's Kelly Taylor than his own Dylan McKay. "My guy was a lot of things, [but] stable wasn't one of them," he told Bill Simmons. "If you're looking out for her in the long term which is what you wanna do, then you gotta do that thing and fall on the sword and let your best friend have her and that's what my guy would do."