At $139M, Florida mansion is most expensive listing

Who will buy Florida's $139 million mansion?

Call it the latest sign of a bubble, or confirmation that the rich still love real estate.

But a new $139 million listing in Hillsboro Beach, Florida—believed to now be America's most expensive public listing—has set a new high-water mark for real estate.

The mansion, called Le Palais Royal, is a "Beaux Arts masterpiece" covering more than 60,000 square feet with 11 bedrooms, 17 bathrooms and an IMAX Theatre. It has a 4,500-square-foot infinity-edge pool with an LED-lit double loop slide and a grand staircase worth $2 million.

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Twenty-two-karat gold leaf finishes and complete soundproofing are featured through the home, which sits on 4.5 acres of beachfront—465 feet on the ocean and 492 feet on the Intracoastal Waterway—where the owner could dock a megayacht. It's also got a 26-foot fountain, putting green and 30-car garage.

The price, of course, may be partly marketing. But the broker for the property, William P.D. Pierce of Coldwell Banker, said he's already had strong interest from buyers, mainly from overseas.

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"We do have some serious inquiries on the property," he said. "The buyers, I think, are from all over the world. Inquiries have been pouring in from Brazil, from Russia, from China, India. Can't forget America. I'm actually surprised [by] the amount of Americans that have been inquiring on this property."

—By CNBC's Robert Frank.