One Park Ave. may be sold all or in part to New York University.

The NYU Langone Medical Center is already the 20-story building’s largest tenant, with 367,584 square feet. It also has rights to lease other floors in the 933,315 square-foot building that sits between East 32nd and 33rd streets.

We found documents that show its early-2011 expansion lease also calls for the owners and lenders to cooperate in creating a “leasehold condominium.” The lease — which doubled NYU Langone’s footprint from roughly 180,000 square feet — was negotiated by a Cushman & Wakefield team led by Bruce Mosler.

No condo documents have been filed yet with the New York State Attorney General.

Industry sources tell us it would make more sense for NYU to buy the entire building and expand at will, but we hear any talks to take it to the next level have stagnated — just like the rest of the economy.

Vornado Realty Trust owns 95 percent of the property, and Murray Hill Properties owns the remainder.

Vornado has also been on a sales spree, agreeing to sell Brooklyn and Long Island malls this week for $1.251 billion with $304 million of its gains going into another property.

A spokeswoman for the medical center commented, “As you know, NYU Langone Medical Center signed a substantial lease at One Park in 2011. This building is a strategic property for the medical center, and our long-term view of its value to our institution remains consistent.”

***

As an extension of its brokerage operations, The Trump Organization is launching Trump International Realty tonight at an event at Trump Tower.

Donald Trump told us the focus is on residential properties and that daughter Ivanka Trump will be in charge. “She’s doing great,” said Trump. “We have a very successful brokerage.”

Ivanka said the new platform will leverage their luxury brands including residences, hotels and golf courses.

“The opportunity here in brokerage is enormous for us, and we are very excited to capitalize on it,” she said.

The Trump Organization’s Kathy Kaye and Kevin Sneddon will head the venture from the current office at 108 Central Park South. Ivanka said she will open another office downtown at a yet-to-be determined location. South Florida, Los Angeles and other world gateway cities will be added to current branches in Chicago and Las Vegas.

***

The team that includes Steven Witkoff, Howard Lorber’s New Valley and New Winthrop Realty is preparing to build an 82,000-square-foot, eight-story retail base at 701 Seventh Ave. in the heart of the Times Square “bow tie” with or without its topping: a 220,000-square-foot, 475-room hotel.

Witkoff told us the two top floors of that structure could be folded into a future hotel for food and beverage use. Any hotel construction may also ride on any deal with up to three retailers for the remaining six floors totaling 70,000 square feet.

“They may not want to go through a hotel construction,” Witkoff said.

He expects retail rents to fetch more than $2,200 per foot because tourist traffic could be greater than that on Fifth Avenue.

Witkoff hasn’t had time to even start a search for a suitable hotel — like the W across the street — for the site on the northeast corner of West 47th Street in the heart of Times Square.

The building will also have an LED sign of 24,000 square feet, making it the largest in the area, according to Witkoff, who spoke yesterday at a Midtown gathering organized by law firm Schulte Roth & Zabel.

***

Colt’s Neck, NJ-based Retro Fitness is opening four locations in Brooklyn and another in Staten Island. The club already has more than 100 locations in New Jersey based on a $19.99-per-month membership-fee model.

Jack Terzi of Jack Terzi Real Estate has represented the club in these deals and as the fitness chain searches for more space in Manhattan.

The company leased 17,000 square feet at 1623 Flatbush Ave., near Target and Brooklyn College, where the asking rent was $500,000 per year.

At 325 Ave. Y, Retro signed for 15,000 square feet with an annual asking rent of $400,000.

In Downtown Brooklyn, near the Barclay’s Arena at 252 Atlantic Ave., Retro will move into 15,000 square feet that had an annual asking rent of $600,000.

For the first fitness club, to be located in Brownsville, the company signed an 11,500-square-foot deal at 81 E. 98th St. with an asking rent of $350,000 per year.

The Staten Island deal for 11,000 square feet is above Trader Joe’s at 23-85 Richmond Ave., where the asking rent was $400,000 per year.