The management are happy to show visitors the suite, if it's unoccupied, but they don't know exactly what happened in there on Labor Day in 1921 - no-one does.
One thing is clear: In Room 1219 that afternoon, an actress by the name of Virginia Rappe was screaming in agony on a bed.
Later that week she was dead.
And the man charged with her death was Roscoe "Fatty" Arbuckle, Hollywood's first one-million-dollar star.
Public enemy No 1The case against the silent movies' king of slapstick would be Tinseltown's first major scandal.
"This was the guy who discovered Buster Keaton; who helped mentor Charlie Chaplin," says Arbuckle biographer Stuart Oderman. "He had magical comic timing. He was one of the all-time greats."
But overnight, the roly-poly buffoon adored by children across America was public enemy number one, and people were spitting in his face outside court.
It was on 5 September 1921, that Arbuckle ended up at a party in a luxury suite on the 12th floor of the St Francis, after taking a break from a hectic filming schedule.
Among the guests was Virginia Rappe, a 30-year-old struggling actress who suffered from chronic cystitis, a bladder inflammation.At some point, Arbuckle and Rappe ended up together in a bedroom from where, a few minutes later, her screams were heard.
Rape allegationGuests rushed in to find Rappe, fully dressed, writhing in pain on the bed.
Arbuckle told them - it was a story he always stuck to - that he had gone to use the bathroom where he found Rappe in a drunken faint on the floor.
He had merely carried her to the bed and she had fallen off, insisted Arbuckle.
But then Rappe uttered the words that would damn the star: "He did this to me."
As Arbuckle left the party, revellers initially assumed the actress was just drunk.
But her condition worsened and when she was finally taken to hospital three days later her friend, Bambina Maude Delmont, told the doctor Arbuckle had raped Rappe.
A medical examination found no evidence of sexual assault.
Death penalty urgedA day later Rappe died from peritonitis, caused by a ruptured bladder.
Arbuckle was charged with first-degree murder, eventually reduced to manslaughter.
With morality groups demanding he face the death penalty, movie moguls ordered Arbuckle's industry friends to disown him.
Los Angeles-based film historian Cari Beauchamp says: "This was the first scandal in Hollywood with box office implications.
"Everyone had believed the stars were covered in fairy dust. Now that illusion was shattered and studio bosses were terrified it would destroy Hollywood itself."
With no concern for prejudicing the trial, the sensationalist "yellow journalism" Press churned out lurid stories of Tinseltown's depravity alongside coverage of the case.
Although Arbuckle was never tried for sexual assault, this notion has endured, largely because of how the trial was reported at the time.
Extortion plotThe star, thought to have weighed about 260lb (118kg), was portrayed as a fat brute who had pinned down his prey, rupturing her bladder.
Luckily for Arbuckle's lawyers, the case was riddled with holes.His chief accuser, Bambina Maude Delmont, was a convicted criminal who had admitted plotting to extort money from him. She never took the stand.
And it emerged in court that the prosecution had used intimidation to force several witnesses to testify against Arbuckle.
Even so, the actor was tried three times. The first two cases ended in hung juries.
After a third trial in 1922, the jury took just a few minutes to unanimously acquit Arbuckle - he was found guilty only of drinking bootleg alcohol.
"Acquittal is not enough for Roscoe Arbuckle," the jury said in a written apology. "A grave injustice has been done."
Although cleared, Arbuckle faced ruinous legal bills and a public still widely convinced of his guilt. He was often heckled in the street.
The case led to the establishing of a Hollywood censorship board, which ruled that Arbuckle should never work in the industry again.Although that ban was later lifted, the actor remained blacklisted unofficially.
For Tinseltown, of course, the show went on - it survived the Arbuckle affair, just like it has weathered many other scandals since then.
As Los Angeles Times film critic Kenneth Turan says: "Stars still get into trouble and they still need help managing crises. At least Arbuckle didn't have to deal with Twitter."
Roscoe Arbuckle spent more than a decade on the comeback trail - during which time he worked under a pseudonym and discovered Bob Hope in Cleveland, Ohio, in 1927.
Mystery lingersArbuckle's rehabilitation was finally complete when Warner Bros offered him a feature-film contract in 1933.
After it was signed, he reputedly said: "This is the best day of my life."
That night he died of a heart attack in the arms of his third wife. He was 46 years old.
Mississippi-based Arbuckle historian David Pearson says the star was the inspiration to many overweight comics, such as John Belushi, Benny Hill, John Candy and Chris Farley.
Like many experts on the case, Pearson is convinced Arbuckle did not harm Rappe.
"Arbuckle was just a film star who was in the wrong place at the wrong time," says Pearson. "And he paid for it for the rest of his life.
"Rappe was definitely in the wrong place at the wrong time because she wound up dead. It was a double tragedy."
But nine decades on, the mystery remains: why did Virginia Rappe die?