Manhattan House, the monolithic Upper East Side building that until last week was the center of a long-running legal battle, is finally ready for its close-up.

The former rental building, which takes up the entire block between 65th and 66th streets and Second and Third avenues, has about 50 apartments on the market, with as many as 500 more expected to go on sale over the next several months.

The conversion of Manhattan House into condominiums has been years in the making, with the project plagued by a lawsuit involving the two investors who bought the building, as well as a lawsuit filed by entrenched tenants to fight the condo conversion. Now that the investor lawsuit has been settled and most tenants have also acquiesced, real estate brokers are revving into action.

“This is taking up most of my time,” the Prudential Douglas Elliman broker coordinating sales, Dolly Lenz, said. “This is the most inventory that’s ever come in this neighborhood and we’ve had more people in here than I can tell you.”

With Ms. Lenz at the helm, a team of seven brokers has quietly begun showing the condominiums; the building’s first open house is scheduled for next week and listings will go online today.

The apartments will range between $1,400 and $2,300 a square foot, more than the $1,139 a square foot average for the neighborhood, according to appraisal firm Miller Samuel. The 22-story 1950s white-brick building, which spawned several less successful copies, has 583 units. A number of the apartments, however, will likely be combined to create larger spaces. The most expensive unit is likely to be a two-apartment combination that will result in a $14 million, 6,000-square-foot corner penthouse with outdoor space, four wood-burning fireplaces, and four bedrooms.

The building has already gone through $150 million in upgrades, including central air-conditioning and new windows, and a washer/ dryer unit for each apartment. About half of the apartments have outdoor space and 40% have fireplaces, Ms. Lenz said.

After the first 50 apartments are finished and sold, prices will be raised the next round of sales will begin.

A pair of investors, N. Richard Kalikow and Jeremiah O’Connor, bought the building, a complex of five connecting towers, in 2005 for $623 million. The price tag, which came to more than $1 million for each apartment, was a record for a building of more than 50 units. As the redevelopment began, the two developers clashed over plans for the building.

In June, a state Supreme Court judge ordered that one partner buy out the other. According to published reports, Mr. Kalikow planned to buy Mr. O’Connor’s stake. Last week, after obtaining $750 million of financing from a German bank, HSH Nordbank AG, Mr. O’Connor was the one who took over the project.

Experts expect sales to be strong.

“On the Upper East Side, inventory is practically nil at this point,” the executive director of Halstead Properties, Charles Urstadt, said. “We are desperate for product here. This will help answer that need.”

A real estate lawyer, Adam Leitman Bailey, said the infusion of so many condominiums had the potential to lower prices in the area. “If anything is going to bring it down, it will be the flooding of a couple more hundred units onto the market,” he said.

The building is in contrast to much of the development popular in the city these days. While many new developments are being designed with sleek, modern upgrades, Manhattan House is getting fitted with more classical amenities. New owners will have access to “Manhattan Club” on the top floor, a lounge where breakfast will be served in the morning and newspapers and magazines will be available. There will be a library “with books from around the world,” Ms. Lenz said. At night, residents will be able to get a cocktail and watch sports on two large-screen TVs. Large terraces, a gym, and a spa will be accessible on the same floor.

The firm Sasaki Associates will be landscaping the building’s private garden and other outdoor areas. The firm designed the 2008 Beijing Olympic Green and is working on gardens surrounding the American University of Cairo, according to the company’s Web site.

“Besides being luxurious and wonderful, it’s housing on the Upper East Side,” Ms. Lenz said. “There is a lot of interest from empty nesters — people who moved to Tarrytown or Greenwich.”