Thirty years after “football head” first wandered the streets of fictional Hillwood, Brooklyn is still hiding in plain sight all over “Hey Arnold” — in its brownstones, stoops, playgrounds, schoolyards and even its jazz-heavy soundtrack.

The Nickelodeon cartoon, which debuted 30 years ago, was technically set in the fictional city of “Hillwood,” which the show’s creator, Craig Bartlett, said was based on Brooklyn, Seattle and Portland. But to many viewers and fans, it was always all about Brooklyn.

Justin Shenkarow, who played the show’s somewhat beloved bully, Harold, remembers that connection well.

“We took inspiration from Brooklyn, from P.S. 118 where all of us kids, the characters in the show, went to school,” Shenkarow said. “The classrooms, with our principal, friendships, talking about our life, getting into trouble. Going on the playground, the baseball field we created on our own.”

The buildings, blocks and building blocks of this world were Brooklyn, often seen through the eyes of creatives in California who knew Kings County.

“The whole ‘Hey Arnold!’ set — the brownstones, the buildings — they all were from Brooklyn,” Shenkarow added. “The neighborhood. We have a little baseball field close to an alley. It feels reminiscent of kids in Brooklyn.”

The show was recorded far from Brooklyn in Burbank, but the beauty of it was, if sometimes somewhat idealized, a bit of the borough.

“It wasn’t technically set there, but it was inspired by Brooklyn. It’s funky, creative, colorful and cool,” Shenkarow, who still spends time in New York City, said. “Even the soundtrack of ‘Hey Arnold!’ is jazz.”

Justin Shenkarow, who voiced Harold on “Hey Arnold!,” said the show’s Brooklyn influence was apparent in everything from its buildings to its soundtrack.

Although Shenkarow grew up in Redondo Beach, Los Angeles, he also went back and forth to Brooklyn and Manhattan when he grew up.

“It was Fort Greene, Bed-Stuy, Williamsburg,” he said. “I had a lot of friends when we graduated from college who moved there. They lived around there.”

If there was ever an episode that felt like it could have been pulled straight from a Brooklyn block, it was “Stoop Kid,” about a character who never left his stoop.

Shenkarow’s character Harold says, “Stoop Kid’s afraid to leave his stoop,” after which Stoop Kid yells back, “I’m going to roll you down the hill, fat boy.”

“People quote those lines all the time,” Shenkarow said.

Harold (far right), voiced by Justin Shenkarow, often played the bully but had a “huge heart,” according to Shenkarow.Screenshot via YouTube

But the Brooklyn influence was more than brownstones and stoops. The characters themselves were part of what made the show feel like a real neighborhood.

Shenkarow said “Hey Arnold!” was done differently than most shows, creating an ensemble feel.

“What was cool and unique about recording [was that] typically when you go in for a cartoon, you go in as one actor, read your lines and you’re done,” he told Brooklyn Paper. “With ‘Hey Arnold!’ they would bring in the entire cast.”

Each cast member would read from the script at a music stand with a microphone in a big room.

“We would get notes from the director and be able to infuse our charisma and character into performances,” he said. “We would read the script again. They would have two full tapings. They would choose the best dialogue per character.”

The process, he said, was a great way to create relationships between characters, as well as actors.

“We were able to look at each other while we performed and see the behavior,” Shenkarow said. “We’re moving our hands, gestures with our faces. It was really helpful to enhance our performances, being in the room with each other.”

The cast developed relationships, getting to know each other off-screen in ways that may have benefited their on-screen performances.

“We became great friends,” he said. “We recorded once a week together. I think that friendship showed up in the show as well.”

P.S. 118, the fictional school attended by Arnold and his classmates in “Hey Arnold!,” appears alongside an elevated roadway reminiscent of the Brooklyn-Queens Expressway.Screenshot via YouTube

That chemistry helped make the characters feel less like cartoon archetypes and more like kids growing up together.

Shenkarow believes the people and plots became part of viewers’ world, providing the fuel to keep the show fresh.

“The characters were rich and layered, not one-dimensional,” he said. “Harold was a bully from the outside. When you got to discover him, you realized he was a sensitive kid with a huge heart. He wanted to be in the friend group.”

Shenkarow said although Harold was a bully on the playground, he learned a lot of lessons and still had a soft side.

“He would get into trouble and have to work at Mr. Green’s butcher shop and learn how to be a butcher. He enjoyed that,” he said, also remembering the episode where Harold had a Bar Mitzvah. “Arnold told me, ‘This is important. I respect what you’re doing. You’re becoming a man.’”

Elliott Gould played the rabbi in that episode, as Shenkarow called his character possibly the “number one Jewish animated character in the history of cartoons,” ahead of others such as Tommy Pickles in “Rugrats.”

The “Hey Arnold!” cast developed a close friendship while recording the show together, with Justin Shenkarow recalling the ensemble as feeling like a group of real-life friends.© Nickelodeon

Shenkarow worked on the show from age 12 in 1994 through age 37, including the 2002 film “Hey Arnold!: The Movie” and the 2017 “Hey Arnold!: The Jungle Movie.” He has continued working in animation and television, including roles on “Spidey and His Amazing Friends” and “Recess,” but “Hey Arnold!” remains the role that continues to connect him with fans.

“Nineties nostalgia is massive now,” Shenkarow said. “It’s the number one Nickelodeon cartoon from the 90s.”

Three decades later, Arnold and his friends haven’t exactly disappeared. The show continues to attract millions of fans on social media and through streaming on Paramount Plus, as well as on demand through Amazon Prime Video, Apple TV and other services.

Some cast members recently reunited at the Skirball Cultural Center in Los Angeles to attend the MultiCon fan pop culture convention.

Rumors of a cast reunion surfaced before being swatted away, but the gathering was another reminder that “Hey Arnold!” hasn’t lost its hold on viewers more than two decades after its five-season run, which aired from Oct. 7, 1996, to June 8, 2004.

As for a possible reboot, Shenkarow isn’t sure whether it will happen, though he likes the idea.

“I don’t know. That’s above my pay-grade in terms of what studios decide,” he said.

Shenkarow’s take, however, is clear.

“The fans want it back. I want it back.”