In the late 1960s, a B-movie producer, a filmmaker untested in America, and a TV star untested on the big screen got together to make a horror movie. They produced a classic.

Rosemary’s Baby is a kind of godmother to all of the Satan-themed horror films that followed it, from The Exorcist to The Omen to The Exorcism of Emily Rose. It’s scary yet elegant, eerie yet oddly romantic, horrifying yet beautiful in its design. It’s the product of a meticulous director who went over his shooting schedule, a young star who persevered even in the midst of a divorce, and a cast and crew who may have ultimately suffered a curse for their part in it.

As the film nears its 50th anniversary, here are 13 facts about Rosemary’s Baby.

1. WILLIAM CASTLE ORIGINALLY WANTED TO DIRECT IT.

Even before Ira Levin’s novel hit bookstores, Rosemary’s Baby became a hot property in Hollywood. The galleys of the novel caught the eye of director/producer William Castle, best known for B-movie horror films like The Tingler and House On Haunted Hill. Castle, eager to make a prestigious film, snapped up the rights to the book, and sought a deal with Paramount Pictures to get the film made. Producer Robert Evans also saw potential in the novel and agreed to adapt it for the screen, but insisted that Castle only work on the film as a producer. Castle, who’d hoped to direct the film himself, reluctantly agreed.

“It was too good for Bill Castle,” Evans later said

Evans ultimately decided on Roman Polanski, who made his American debut with the film, to direct Rosemary’s Baby.

2. ROMAN POLANSKI MADE ONE VERY SIGNIFICANT STORYTELLING DECISION.

Roman Polanski and Sharon State attend the premiere of 'Rosemary's Baby.'

When Evans offered him the film, Polanski was immediately engaged by Levin’s novel, and decided to write the screenplay himself. He had little difficultly, but as an agnostic, there was one particular aspect he wanted to remain intact onscreen: ambiguity. He set out to tell a story where, in theory, you could perceive everything that happened to Rosemary as something she was imagining.

“Being an agnostic, however, I no more believed in Satan as evil incarnate than I believed in a personal god; the whole idea conflicted with my rational view of the world,” Polanski later said. “For credibility’s sake, I decided that there would have to be a loophole: the possibility that Rosemary’s supernatural experiences were figments of her imagination. The entire story, as seen through her eyes, could have been a chain of only superficially sinister coincidences, a product of her feverish fancies … That is why a thread of deliberate ambiguity runs throughout the film.”

3. IRA LEVIN MADE DRAWINGS OF THE BRAMFORD APARTMENTS.

Prior to shooting Rosemary’s Baby, Polanski gathered the cast for rehearsals on soundstages, complete with taped-off layouts of each apartment (the interiors were all shot on constructed sets) to give the actors an idea of how their movements would work within the eventual sets. Helping that process along was Levin himself, who provided detailed layouts of the apartments.

4. POLANSKI MADE SKETCHES TO CHOOSE THE SUPPORTING CAST.

Ruth Gordon in 'Rosemary's Baby.'

When it came time to choose the supporting cast, Polanski did something a little unorthodox: He drew them. Feeling that each resident of the Bramford needed a very particular look, he felt that it would actually be easier if he simply showed those looks to the Paramount casting director. So, he made sketches of each Bramford resident and turned them over to the studios. That’s how actors like Ruth Gordon and Sidney Blackmer made their way into the film.

5. ROBERT REDFORD WAS THE FIRST CHOICE FOR GUY WOODHOUSE. 

In casting Rosemary’s Baby, Evans and Polanski didn’t always agree from the start, so several different incarnations of the cast were possible. They did, however, agree that Robert Redford would be perfect for the role of Guy Woodhouse, Rosemary’s ambitious actor husband. Unfortunately, Paramount and Redford were locked in a contractual dispute at the time, so he wasn’t available. So the studio went searching, and other choices included Robert Wagner, Richard Chamberlain, James Fox, Laurence Harvey, and Jack Nicholson (who actually tested for the role). Ultimately, Polanski decided on John Cassavetes, a talented filmmaker he was already familiar with.

6. MIA FARROW WAS NOT POLANSKI’S FIRST CHOICE FOR ROSEMARY.

Mia Farrow on the set of 'Rosemary's Baby.'

For the role of Rosemary Woodhouse, Polanski set out to find an “All-American” actress. His choice was Tuesday Weld, then known for her work in films like The Cincinnati Kid. Evans and Castle had a different idea: Mia Farrow, then best-known for the TV series Peyton Place. After auditioning a few actresses, Polanski ended up agreeing that Farrow was right for the role.

“Mia was a little left-of-center. That’s the reason we wanted her,” Evans said. “She wasn’t just another pretty face.

“She had another dimension. And what she didn’t have, Roman got out of her.”

7. POLANSKI CLASHED WITH THE STUDIO DURING PRODUCTION.

Rosemary’s Baby was Polanski’s first American film, and his attention to detail ultimately created some problems with Paramount. According to Evans, the director fell behind his shooting schedule very quickly, to the point that Castle was calling and warning him that problems were ahead. Evans and Castle, according to Polanski, stood by their director, and it also didn’t hurt that the footage coming back from the film was impressive. In Polanski’s recollection, it took a fellow director—the great Otto Preminger (Laura, Anatomy of a Murder)—to convince him he had nothing to worry about. In a chance meeting on the Paramount lot, Polanski explained his schedule problems to the legend. Preminger asked him about the “rushes,” the raw footage screened for studio executives. When Polanski explained that Paramount seemed to love his footage, Preminger put him at ease.

“‘So what do you care?’ he says,” Polanski recalled. “‘They never fired anyone because of schedule, because of lagging behind, but if they don’t like the rushes, you’re out very soon.’ So, that was the case. They really liked the material very much.”

8. POLANSKI AND JOHN CASSAVETES CLASHED DURING PRODUCTION, TOO. 

John Cassavetes and Mia Farrow in 'Rosemary's Baby.'

John Cassavetes is still remembered as a titan of independent film, known for his freewheeling, improvisational productions like A Woman Under the Influence. Polanski is a different kind of director, known for his precision. Though Cassavetes was only working as an actor on Rosemary’s Baby, their respective filmmaking styles still clashed. According to Farrow, Cassavetes longed to improvise and let the moment carry him through the scene, while Polanski would be annoyed if an actor lifted a glass mere inches from where he imagined it to be. Though Polanski and Cassavetes knew each other, and apparently liked each other, prior to filming, their working relationship became a bit strained.

“John Cassavetes was not my best experience, I must say,” Polanski recalled.

9. FARROW REALLY WALKED OUT INTO NEW YORK TRAFFIC.

According to Farrow, Polanski’s directing style often involved him acting out the scenes himself to show the actors what he wanted, and this apparently had the effect of convincing Farrow to do a few outrageous things. For example, she ate raw liver on camera through several takes, even though she was a strict vegetarian. The most extreme instance of this, though, came during the sequence when Rosemary is attempting to flee the Bramford and walks out into traffic in an effort to quickly cross the street. This was not a carefully orchestrated sequence in which streets were blocked off and stunt drivers were employed. According to Farrow, she really did just simply walk out into a New York street and hoped the oncoming cars would stop. This was Polanski’s idea, and he assured Farrow that “Nobody will hit a pregnant woman.” He was right, and the scene was shot several times, with one caveat: Polanski himself had to operate the camera, because no one else dared to.

10. FRANK SINATRA FILED FOR DIVORCE FROM FARROW DURING PRODUCTION.

The wedding of Frank Sinatra and Mia Farrow.

At the time of Rosemary’s Baby’s production, Farrow was famous for two things: Starring in Peyton Place and being married to legendary singer Frank Sinatra. When Farrow got the script for Rosemary’s Baby, she asked Sinatra to read it, and after he finished he turned to her and said “I can’t see you in it.” Farrow agreed to do the film anyway, but as Polanski’s shooting schedule stretched out it began to conflict with a planned role in Sinatra’s own film, The Detective. Farrow hoped she could make the schedules work and do both films, flying coast-to-coast in the process, but ultimately Rosemary won out, and Sinatra issued a demand that she choose between the movie or her husband. When she decided to finish Rosemary’s Baby, he sent his lawyer to the set to deliver divorce papers. Farrow signed them in “a blur of tears,” then continued shooting.

The incident created such tension that Sinatra and Evans didn’t speak for several years, to the point that Evans would call restaurants and ask if Sinatra was dining there before he decided to go. According to Farrow, she and Sinatra remained friends until his death in 1998.

11. WILLIAM CASTLE THOUGHT THE FILM WAS CURSED.

According to Farrow, actor Sidney Blackmer (who played coven leader Roman Castevet) once said on set “No good will come of all this ‘Hail Satan’ business,” and apparently he wasn’t the only one who thought so. William Castle later became convinced the film was cursed. Shortly after production he suffered gallstones to such a severe extent that he required surgery. As he recovered from that illness, Rosemary’s Baby composer Krzysztof Komeda suffered an accidental fall that led to a coma and, eventually, his death. Then, in the summer of 1969, actress Sharon Tate—Polanski’s wife—was infamously murdered by the Manson Family. For Castle, it all added up.

“The story of Rosemary’s Baby was happening in real life. Witches, all of them, were casting their spell, and I was becoming one of the principal players,” he later recalled.

12. CASTLE MADE A CAMEO.

Castle initially wanted to direct Rosemary’s Baby himself, and had to settle for a producer’s role instead. He did also get to act a little in the film. When Rosemary goes to the phone booth to call Dr. Hill’s office, a man with a cigar comes up and waits outside. Because the paranoia level in the film is so intense at this point, the viewer initially wonders if the man is part of the conspiracy against Rosemary. Ultimately, he’s a man just waiting to use the phone. The man is Castle.

13. THERE ARE TWO DIFFERENT SEQUELS.

Rosemary’s Baby was an instant hit, and the Satanism woven into its plot ultimately started a craze that led to other hits like The Omen and The Exorcist. So, naturally, a sequel was in the cards. In 1976 a made-for-TV movie titled Look What’s Happened to Rosemary’s Baby aired on ABC during the Halloween season. It stars Patty Duke as Rosemary, was directed by Rosemary’s Baby co-editor Sam O’Steen, and even features the return of Ruth Gordon as Minnie Castevet.

In 1997, Levin himself produced a sequel, a novel titled Son of Rosemary. The film was also remade as an NBC miniseries in 2014, starring Zoe Saldana as Rosemary.