The year is 1969. The place is Los Angeles.

But Hollywood, really.

A ruggedly handsome, old-school, 45-ish man is driving a cream-colored Cadillac the size of a small boat. He is stopped at a red light when a hippie girl in jean shorts and a halter top glides in front of the car.

She might as well be from Mars for all they have in common.

Once Upon a Time in Hollywood: 4 out of 4 CST_ CST_ CST_ CST_ CST_ CST_ CST_ CST_ Columbia Pictures presents a film written and directed by Quentin Tarantino. Rated R (for language throughout, some strong graphic violence, drug use, and sexual references). Running time: 159 minutes. Opens Thursday at local theaters (in 70mm at the Music Box Theatre).

But when she flashes a carefree smile and gives him the peace sign, a grin cracks his stoic demeanor, and it feels like this might be the first time he’s willing to accept, if not completely understand, how the world is changing at tornado speed and he’s on his way to becoming a relic from another time.

Quentin Tarantino’s deeply personal, ’60s-cool, darkly funny, trippy, bold and sensational “Once Upon a Time in Hollywood” is filled with pitch-perfect vignettes such as that moment at the intersection — moments perfectly capturing the vast chasm in the country and in the world of American pop culture in 1969.

It was a time when safe, conventional Westerns such as “Bonanza,” “Gunsmoke” and “Daniel Boone,” cornball rural comedies “The Beverly Hillbillies” and “Mayberry, R.F.D.” and law enforcement dramas “Dragnet” and “The F.B.I.” were Top 20 TV shows — in sharp contrast to counterculture, antihero movie hits such as “Midnight Cowboy” and “Easy Rider.”

Television was for Mom and Dad. The movies were for their teenage and early 20s offspring, who were off doing God knows what, God knows where.

In certain elements of tone and structure, “Once Upon a Time In Hollywood” has echoes of “Pulp Fiction” and “Jackie Brown,” but it is alive and electric with a beat all its own.

This is a brilliant and sometimes outrageously fantastic mash-up of real-life events and characters with pure fiction. Tarantino, who was 6 years old in 1969, has created a stylized, at times idealistic, sometimes insanely inspired memory piece — a love letter to the movies from a director famously obsessed with movies.

It’s also a fractured fairy tale. (After all, it IS called “Once Upon a Time in Hollywood.”) And it is absolutely dripping with pop-culture touchstones and a flood of references to other movies, on a level both exhilarating and borderline overwhelming. Do you have to “get” every reference, from period-piece TV shows such as “Mannix” and “The FBI” to “The Green Hornet,” to the titles of the movies on the marquees, to the songs on the radio that often mirror or foreshadow events and characters?

Absolutely not. (But it’s great fun if you do.) For all its deep drilling into the popular culture of the time, for all of its poetic license, “Once Upon a Time …” also tells the familiar Hollywood tale of rising stars and fading stars in a changing industry.

It’s also a modern-day Western about an actor who starred on a TV Western and is now reduced to guest-starring on a pilot for a Western starring a new up-and-comer.

In one of the great buddy-pairings of the decade, Leonardo DiCaprio and Brad Pitt play Rick Dalton and Cliff Booth, who have been best friends ever since Rick starred in a late 1950s TV show called “Bounty Law” and Cliff was his stunt double.

That’s as good as it got. As the story goes, Rick was briefly considered for a showcase role in “The Great Escape” when Steve McQueen wavered about taking the part — but the closest Rick actually came to feature film glory wasn’t very close at all. It was a World War II B-movie titled “The 14 Fists of McCluskey.” (We see a scene from the “movie” in which Rick as McCluskey yells, “Anyone order fried Sauerkraut!” before torching a room full of Nazis with a flame thrower.)

Save for the occasional flashback, “Once Upon a Time …” takes place over three days in 1969: February 8, February 9 — and Aug. 8.

No longer in demand as a lead, Rick has been playing heavies on a series of episodic TV shows, while Cliff has had to transition from stunt man to Rick’s driver/assistant/handyman/you name it.

Rick lives in a house on Cielo Drive in Benedict Canyon. He has yet to meet the new next-door neighbors — the red-hot film director Roman Polanski (Rafal Zawierucha) and his girlfriend, actress Sharon Tate (Margot Robbie) — but as he tells Cliff, he’s hoping for an introduction at some point because you never know, it could lead to Rick appearing in the next movie by the director of “Rosemary’s Baby.”

When the focus shifts from the Rick/Cliff storyline to Sharon, “Once Upon a Time …” takes on a sweet and sunny tone. With relatively little screen time, Robbie lights up the screen as Sharon dances to the sounds of Paul Revere and the Raiders, squeals in delight when meeting friends such as Michelle Phillips at a party at the Playboy Mansion, and beams with pride as she announces to the ticket taker at a showing of “The Wrecking Crew” she’s actually in that movie.

We’re never far from the world of movies and TV (and particularly Westerns) in this movie, even when the story takes us to the Charles Manson compound, which was on the old Spahn Ranch in Los Angeles County — site of movies such as “The Outlaw” and episodes of TV Westerns. An extended sequence set on the ranch is chilling and tense, and then something else, and I’ll say no more.

In typical Tarantino fashion, “Once Upon a Time” features a bounty of colorful cameos, including appearances by QT favorites such as Kurt Russell, Michael Madsen, Bruce Dern and Zoe Bell; Al Pacino as a bottom-feeder agent lobbying Rick to revive his career by doing spaghetti Westerns; Lena Dunham and Dakota Fanning as two of Charles Manson’s zombie disciples; Damian Lewis as Steve McQueen, and the late Luke Perry in his final film role as an actor whose career path briefly intersects with Rick’s.

(Margaret Qualley is a standout as a fictional Manson girl who catches Cliff’s attention.)

Shot on Kodak 35mm film by the great cinematographer Robert Richardson, “Once Upon a Time in Hollywood” pops with stunning visuals, including some beautiful, sweeping, overhead shots giving us a big-picture perspective on certain events.

DiCaprio strikes just the right seriocomic notes as Rick, who is more than a little narcissistic and kind of an idiot but earns our sympathy because he wears his heart on his sleeve and he truly cares about his friend Cliff.

And then there’s Mr. Pitt. Who kills it.

Some 26 years after his stoner-classic scenes in the Tarantino-scripted “True Romance” (“Get some beer … and some cleaning products”) and a decade after starring in Tarantino’s “Inglourious Basterds,” Pitt turns in one of the most memorable performances of his career as the badass and fearless, albeit deeply flawed, antihero Cliff. In a movie filled with sparkling acting, Pitt dominates.

It’s one of the best performances of the year in one of the best movies of the year.