LOS ANGELES — Melissa McCarthy has long since decamped to the West Coast, but the Plainfield native says, “I will always consider Chicago my hometown — because it is, and is such an integral part of who I am as a person.”

While most of her new film “The Boss” (opening Friday) was shot in Atlanta, it’s set in Chicago, and McCarthy, co-star Kristen Bell and several other castmates traveled to Our Town to film iconic exteriors.

One of them was the former Playboy Mansion, once owned by Hugh Hefner — now converted into exclusive condominiums on the city’s North State Parkway. In the movie, the structure serves as the exterior of the mansion previously owned by McCarthy’s once-wealthy financier character, Michelle Darnell, now flat broke after going to prison for insider trading.

McCarthy laughed as she recalled how she “weaseled my way into that house. I’m such a fan of old architecture, and that’s one beautiful building!” The actress spotted a woman exiting the building while they were filming outside, “and I asked her if I could get inside. She was so gracious. I don’t usually do this, but I did play the celebrity card,” said McCarthy with a laugh. “I even got to see the trap door that led to the grotto, back when Hefner lived there — saw the pole that led down into the grotto and the whole bit.”

McCarthy’s love of the city is genuine. After all, her long-running hit sitcom “Mike & Molly” (which ends its six-season run next month) also is set in Chicago. “However, for this movie, we were careful, and very specific on what to show about Chicago.

“I think there’s a feel you get from Chicago when you’re there. I feel the whole movie kind of feels like that. It was important to get that across. There where shots on the [Michigan Avenue][ bridge that brought flashbacks to me as a kid being there. I couldn’t believe we were actually here standing by all these things — and I remember how I felt the first time I saw them as a child.  I frankly got a little choked up during some of that filming. I got very sentimental. I was totally hometown proud.”

As for the over-the-top character she plays in “The Boss,” McCarthy admitted, “Michelle has been with me a long time — 15 or 16 years. She doesn’t look that different from when I created her at the Groundlings [the L.A. improv club, similar to Second City]. She still has that short, spiky red wig, that turtleneck — all of it from when I fell in love with her years ago. She came out of me as a very specific woman, energy and look.”

McCarthy, who co-wrote the film with her husband Ben Falcone, the film’s director, revealed that Michelle Darnell was largely inspired by the late hotel “queen of mean” Leona Helmsley, “with a dash of Martha Stewart and perhaps a dollop of a female Donald Trump thrown in as well — but before anyone knew about his politics.”

As is often the case, McCarthy gets to show her flare for physical comedy in “The Boss” — including a wild sword battle with business rival Renault, played by “Game of Thrones” star Peter Dinklage. McCarthy said, “I do love it — the physical comedy. But people are what they are — or at least I am — by how you move. It’s such a big part of me and the characters I play. It just goes hand in hand. I don’t know how to separate them.”

One example of how McCarthy showcases her physical comedy chops — literally – is in a teeth-whitening scene early in the film. McCarthy’s diva-esque Michelle insists her long put-upon assistant Claire (Kristen Bell) perform a daily teeth-whitening procedure in Michelle’s office.

The joke comes from watching McCarthy continuing to bark orders while her mouth is distorted into a weird (but hilarious) position. They had a hard time getting through that entire filming process, keeping straight faces. “Trust me, there were tons of outtakes! That is not a natural position to stay in for an entire shoot. You cannot physically do that without an enormous amount of drool flowing. You can’t hold your mouth like a Pez dispenser and not have some dribble.

“And every time I’d drool, I’d start to laugh, and then Kristen would crack up and we’d be done in!”