The oldest gym of its kind in New York City is all new, and more popular than ever.

Eighty years after it was founded in the heart of the Bronx, The Hub at 149th St. and Third Ave., and three decades after arriving in Brooklyn, Gleason’s Gym is thriving in new quarters in the shadow of the Manhattan Bridge.

“It’s busier now than it’s ever been,” said owner Bruce Silverglade. “It’s a good thing.”

The December move covered just a few blocks. The space is a little smaller, but Silverglad kept the workout area roughly the same size by devoting less space to offices. He traded a second-floor location for the first and moved over about half the equipment.

Most notably, he had to leave his boxing rings behind. They couldn’t get the 20x20, one-piece monsters out of the old place, so they bought new ones that piece together. Some new workout machines, bright red paint, familiar pictures and posters on the wall and Gleason’s is Gleason’s.

It’s the latest incarnation for a survivor of a gritty past that fits in fine in one of the city’s hottest neighborhoods.

Three owners, four locations, 134 world champions, 26 movies filmed there — four that took home Academy Awards — and forget about trying to count up all the television shows that have set up their trailers on DUMBO’s cobblestone streets for a scene set among Gleason’s heavy bags.

“There’s not a magazine nationally or internationally you could name that hasn’t shot here,” said Silverglade. “Fashion shoots, they love to bring over good-looking guys and girls and throw them next to some of my guys.”

It’s really the entire history of boxing that has passed through Gleason’s, in one incarnation or another. Jake LaMotta. Muhammad Ali, back before he changed his name from Cassius Clay. Roberto Duran. Gerry Cooney. Riddick Bowe. Mike Tyson. Brooklyn’s own Mark Breland, five-time Golden Gloves champ, Olympic gold medalist and WBA welterweight champion.

But back in the 80s, Silverglade was scrambling a bit. Founder Bobby Gleason — he’d changed his name from Peter Gagliardi to reflect the ethnicity of the gym’s original neighborhood in the Bronx — had passed away in the mid-70s. Silverglade bought in as a partner after Gleason’s had moved to midtown Manhattan. But then they lost their lease.

At the same time, developer David Walentas was moving forward with plans to rehabilitate the warehouses in the waterfront strip between the Brooklyn and Manhattan bridges. He’d bought up nearly the entire neighborhood five years earlier.

“This place was the pits,” said Silverglade. “There were no streets. No sidewalks. All these buildings were non-existent. The newer ones were non-existent. But the older ones were rundown, vacant. There were a lot of squatters living around here.”

The deal had one thing going for it.

“The rent was peanuts,” said Silverglade. “Yeah, we’re coming!”

Thirty years later, it’s a different world. DUMBO is now one of New York’s wealthiest, most-expensive neighborhoods. Upon its arrival in Brooklyn, Gleason’s was populated almost entirely by dedicated boxers. Now the gym has 1,200 members, including kids and 400 women.

In addition to all the film, television and magazine shoots, Silverglade will host art shows, book readings, corporate events, weddings and bar mitzvahs.

“I try to draw people into the gym that wouldn’t normally come into a boxing gym,” said Silverglade. “Boxing still has that tough reputation. Once a person comes in and sees really it’s not tough, I don’t have hoodlums up here, I’ve got athletes that are in good condition. They’re polite, they’re nice. So I try to get as many people in here as possible. Once in a while you get a member from it, not too much, but you get a lot of goodwill.”

With the opening of Barclays Center and its BROOKLYN BOXING platform in 2012, Gleason’s found a natural partner in continuing to promote and grow the sport in Brooklyn.

“Boxing is now centered basically out of the Barclays Center in New York City and it’s been great,” said Silverglade. “Because it gives the young athletes an opportunity to aspire to something and get some training in and some competition in. It’s great that it’s in Brooklyn and it’s great that it’s a mile and a half from Gleason’s Gym because I can have that relationship with the Barclays Center.”