Atlantic City, where Donald Trump and Steve Wynn were once fierce rivals before they were friends, is heating up in more ways than one as summer approaches.

Now, an Atlantic City penthouse that once belonged to casino mogul Wynn has listed for $2.19 million. What’s more, it has expanded in size to become a massive 7,500-square-foot duplex.

The residence is on Atlantic City’s iconic boardwalk, overlooking the Atlantic Ocean. When Wynn owned the aerie back in the city’s heyday, he hosted glamorous parties. Guests included legends like Frank Sinatra, who performed at Wynn’s neighboring Golden Nugget Hotel & Casino during the 1980s.

The current owner bought the sky-high Garden State nest for $450,000, and the adjacent unit for $400,000, in 2015 — and then combined them. 

It’s all at the Ocean Club at 3101 Boardwalk. The unit comes with five bedrooms and 6½ baths. Given its history, there’s plenty of space to entertain inside the home, which features a large chef’s kitchen and a roomy area for dining.

Design details include lots of gray and white marble, and a smashing terrace overlooking the ocean. Building amenities include a gym, an indoor pool, and — according to the listing — “a dynamic lifestyle committee that curates engaging social events.” 

The listing broker is Stephanie Luongo of Serhant.

Meanwhile, in Manhattan, Wynn’s massive duplex at the Ritz-Carlton Residences on Central Park South has been off the market for the past six weeks, Gimme Shelter can reveal. 

He bought that 10,875-square-foot duplex for $70 million in 2012. At the time, it was the most expensive residential purchase in the country.

Ten years later, in 2022, Wynn listed it for a staggering $90 million. By 2023, the penthouse price was dramatically slashed to $65 million. But by last August, the duplex was back on the market with a $5 million bump, asking $70 million — before it was taken off the market on March 31.

Sotheby’s Serena Boardman last had that listing.