Pop Art masterpieces were askew on the wall, a creepy 18-foot clown puppet hung from the ceiling, 20 Hells Angels huddled together in sleeping bags on the floor as Dennis Hopper sashayed down the stairs in a flowing caftan robe.

It was just another day in the life at 1712 North Crescent Heights Boulevard in the sixties, a time and place that is the subject of the new book “Everybody Thought We Were Crazy” (Ecco) by Mark Rozzo.

The house, known as just “1712,” was owned by actress Brooke Hayward and her enfant terrible husband Hopper during eight tumultuous years of marriage, and filled to the brim with her found objects and his collection of contemporary art that, as Joan Didion remarked, “seems the result of some marvelous scavenger hunt.”

The house “embodied the collision of Old Hollywood and New, of chic bohemia and burgeoning counterculture,” Rozzo writes, where you could as easily run into the Black Panthers as Jack Nicholson. Jane Fonda called it “a magical house.”

But with magic sometimes comes monsters.

1712 was also where Hopper unraveled. A place where the three children would sometimes have to cower in closets to hide from their increasingly unhinged father, who drank and drugged to extreme excess, who liked to play with firearms and sometimes took his rage out on their mother.

As Hayward once wrote, “Those years in the ’60s when I was married to Dennis were the most wonderful and awful of my life.”

Writer Terry Southern, who penned “Dr. Strangelove,” would sum up the dynamic between Hopper and Hayward with one perfect sentence in 1965: “She is a Great Beauty and he is some kind of Mad Person.”

The two were the unlikeliest couple when they met on the production of the ill-fated Broadway show “Mandingo” in 1961. Hayward was Hollywood royalty — the daughter of super-agent Leland Hayward and actress Margaret Sullivan. She was nursing the wounds of a recent divorce and the dual deaths of her mother and sister, both by suicide. She initially loathed the unwashed and unprepared Hopper.

“He terrified me,” she told Rozzo.

Hopper was the furthest thing from a scion — born in Dodge City, Kansas, he was nearly banished from Hollywood for clashing with the director of the movie “From Hell to Texas” before his 25th birthday.

Despite it all, the two started a passionate romance, bonding over a shared love of the visual. Hayward bought Hopper a Nikon camera for his birthday, starting a lifelong pursuit of photography. (His photographs of ’60s figures like Paul Newman and Timothy Leary have been featured in major galleries around the world.) Overnight, it seemed, the two had become “the coolest kids in Hollywood.”

The couple initially moved into a house destroyed in the wildfires that ravaged Los Angeles in 1961. They then moved to 1712 North Crescent Height Boulevard, a Spanish style home built in 1927 that would become the beating heart of the growing counterculture.

Hopper had a natural eye for art and was one of the first actors to put his wallet behind the growing Abstract and Pop Art movements. Incredibly, the first painting Hopper purchased (with Hayward’s money) was Warhol’s Campbell Soup Cans in 1962. (When Hopper described the piece, Hayward was unimpressed. “It’s going in the kitchen!”)

Hopper spent his free time perusing the nearby galleries, amassing one of the greatest private contemporary art collections of the era — paintings and sculptures from artists like Jasper Johns, Robert Rauschenberg and Roy Lichtenstein.

Hayward did her part in augmenting the surreal décor, collecting treasures at flea markets and antique shops around Hollywood — Tiffany lamps, Victorian spool tables, stained glass windows, a fiberglass car, and an old billboard. She worked on the house herself, tiling the entranceway, for example, wearing only pearls and a bikini. The result was a mishmash of brilliance and surreality that mirrored the mood of the time.

To celebrate Warhol’s arrival on the West Coast, Hopper and Hayward threw a party with members of the art world and actors like Natalie Wood and Peter Fonda. Warhol was gobsmacked — the people looked like “living Pop Art” while his own work was “liberated from galleries” on the walls. He literally “oohed and aahed.” 

“There was a constant stream of people passing through,” remembers Jeffrey Thomas, Hayward’s older son from her first marriage. On any given day, you might find members of the Diggers, a ’60s egalitarian activist group, cooking up heroin in the living room.  

Hayward and Hopper were eccentrics — a quality admired by their peers, but not necessarily by their children. Their daughter Marin was terrified of the art installation called “The Quickie” by Edward Kienholz, where a mannequin head had been mounted on roller skates. “I thought she was decapitated,” she said.

When her parents would pick her from her fancy private school in a yellow Checker cab, she couldn’t help but feel like an outsider. “I felt like Marilyn in The Munsters,” said Marin. “It was embarrassing, frankly, to bring friends over,” said Thomas. “I didn’t want people to see the house. Like everyone else, we wanted to be normal.”

But “normal” was never an option.

As the house’s popularity grew, Hopper’s career sputtered. He had trouble landing roles and couldn’t get his own film “The Last Movie” funded. He took it out on Hayward. “He was very resentful of me being an actress,” she told Rozzo in an interview. “So I gave it up.”

Meanwhile, Hopper grew increasingly reliant on drugs and alcohol. “Dennis always had a bottle of Jack Daniel’s and always had a Coors or Olympia beer in his hand,” Jeffrey Thomas said. “He smelled like alcohol morning and night.”  Dennis would later say that at the time he couldn’t go a day without smoking at least eight joints. One evening, he fell asleep in bed while smoking a joint, which lit the mattress on fire while he kept sleeping. Hayward had to jolt him awake to save his life.

Hayward started to tire of the scene and of Hopper’s near-constant inebriation. When Jane Fonda, her then-husband French director Roger Vadim, and Hopper climbed into bed with Hayward at ten o’clock at night after putting the kids down for bed, Hayward was furious. “I said, ‘Get the f—k’ out.’” By 1968, Hayward started to fear Hopper’s mood shifts. “He seemed to be losing his grip on reality,” Rozzo wrote.

The kids would hear fighting though the walls almost every night.

“You’re a terrible actor.”

“F–k you, Brooke.”

“You’re f–king awful!”

Hayward’s barbs could be brutal — but Hopper was actually violent. He kicked in the windshield of their Checker cab. Almost anything could set him off. He punched Hayward in the nose, breaking it, after she disagreed with him about which of his photographs was best. “I had to go pick the children up at school with a broken nose,” Hayward told Rozzo.

“I slapped a few women,” Hopper would later admit to a Guardian reporter. “I didn’t have any problems treating them much as I would a male.”

Hopper also kept an extensive gun collection. According to Thomas, his stepfather “chased us with a gun to kill all of us. We were going from house to house, trying to lay low. I mean, it was seriously a psychotic episode.”

“I spent a lot of time hiding in closets,” added William, Hayward’s younger son.

When Hopper lost control — chasing the kids or shrieking naked on the roof of the house — Brooke would collect the kids and stay at the Chateau Marmont until things settled.

Her lawyer told her she should leave him. She refused.

The final straw came after Hopper came home berserk after filming “Easy Rider.” He demanded dinner and told her he’d kill her if she didn’t comply. Thomas had to stand between his stepfather and his mother, saying, “Don’t you ever get near my mother.”

‘She is a Great Beauty and he is some kind of Mad Person.’

“Dr. Strangelove” scribe Terry Southern, on Brooke Hayward and Dennis Hopper

She filed for divorce in 1969. “Congratulations on the first smart move you’ve made in six years,” was Brooke’s father’s response when she told him.

“Easy Rider” — which Hopper starred in, directed, and helped write — was an instant cult classic, which should have cemented the career of a person less prone to self-immolation. Even Hayward, who was completely estranged from Hopper and would remain so for several decades, was impressed. “I knew how talented he was. I wasn’t surprised.”

But after its success, Hopper’s career took a nosedive. He exiled himself, drinking “a gallon of rum a day, plus 28 beers on the side. Then I’d do three grams of cocaine.” He was apprehended wandering around naked in a Mexican jungle, masturbating on a tree in the early 1980s. “I thought I’d become a galaxy,” he said. He was briefly placed in a psychiatric hospital and decided to sober up.

It was the start of yet another unlikely return to Hollywood with the 1986 film “Blue Velvet” where he played the unforgettable psycho Frank Booth. A career of ups and downs followed — as did the bad press of four more broken marriages with even more allegations of violence and abuse — until his death at age 74 in 2010. Film executive Peter Bart summed up Hopper: he “excelled as an actor, filmmaker, art collector and photographer and has done everything he can to self-destruct in each of those arenas.”

Hayward’s life took a far less dramatic turn after her divorce. She wrote a bestselling memoir of her life pre-Hopper, moved to New York, where she still lives, and married a bandleader. She has sold most of the paintings from 1712 — including the Warhol soup cans. She used the money to buy her husband a grand piano.  

Though the two were largely estranged, months before Hopper succumbed to prostate cancer in 2010, he asked Hayward to visit him in his Frank Gehry-designed compound in Venice, California.

“You’re the only woman I ever loved,” he told her.

Hayward told him that she loved him, too.

1712 has gone through many owners since its heyday in the sixties — Hayward sold it to film director Walter Hill, who eventually sold it to the original “Daily Show” host Craig Kilborn. Now it’s owned by British interior designer Martyn Lawrence Bullard, who starred in Bravo’s short-lived series “Million Dollar Decorators.”

Time may have passed, but the house still retains its power. Some say the memory is as indelible as a tattoo.

“When I drive by, it looks so little,” said their daughter Marin. “It looked enormous when I was small.”