Noted art collectors Alberto Mugrabi and Aby Rosen are in contract to buy condos in a yet-to-be-completed building in downtown Manhattan, according to people familiar with the deals.

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A rendering of the Schumacher, which is expected to be completed in December, 2014.

Mr. Mugrabi, who helped his family build what iss arguably the largest private collection of Andy Warhol’s art, is in contract to buy two triplex units at the Schumacher that were listed at $10.995 million and $9.7 million. He plans to combine the two spaces for a total of 8,719 square feet, says listing agent John Gomes of Douglas Elliman Real Estate. Mr. Gomes says Mr. Mugrabi’s combined condos will wrap around the building’s central courtyard and includes a southern wall with no windows so Mr. Mugrabi can hang his artwork. Mr. Mugrabi also has rights to display some of his sculpture in the courtyard, which is being designed by Ken Smith, who created the rooftop garden at the Museum of Modern Art.

Separately, Mr. Rosen, a well-known real-estate developer and collector of contemporary art, is in contract to buy a three-bedroom, 3½-bath, 2,408-square-foot condo listed for $8.5 million. Mr. Gomes says Mr. Rosen called him and asked to come by the sales center with a couple of friends. Mr. Rosen brought Mr. Mugrabi, who had “no intention of buying an apartment,” Mr. Gomes says, but he “fell in love with the project.” Messrs. Mugrabi and Rosen didn’t respond to requests to comment.

The Schumacher is expected to be finished in December 2014 by Stillman Development International. It has 20 two- to four-bedroom condos, half of which are under contract. The building will have an oak-paneled library with marble flooring and horsehair rugs, a roof terrace and a pirate-themed children’s playroom. Each condo will include Siberian oak flooring, natural stone walls and a free-standing soaking tub in the master bathroom, custom gray-colored wood kitchen cabinetry and barrel-vault exposed brick ceilings.

Mr. Gomes shares the Schumacher listings with Fredrik Eklund, also of Douglas Elliman.

—Alyssa Abkowitz

A Waterfront House in Darien, Conn., Lists for a Record $30 Million

Noted art collectors Alberto Mugrabi and Aby Rosen are in contract to buy condos in a yet-to-be-completed building in downtown Manhattan. A Darien, Conn., waterfront house is going on the market for $30 million. Alyssa Abkowitz has this week’s Private Properties. Photo: Williams New York.

A 17-room waterfront house in Darien, Conn., is going on the market for $30 million, brokers say, which is believed to be a record asking price for a home in the town along Long Island Sound.

The century-old house is about 17,000 square feet, according to the listing, with eight en suite bedrooms and seven fireplaces. It was stripped down and rebuilt a decade ago to resemble a traditional French country manor, with a steep-pitched slate roof, twin curved limestone staircases and a Gatsby-like granite terrace looking across the water to the Noroton Yacht Club. It is on a 3.7-acre lot with a pool, a long deep-water private dock and formal gardens.

The house is owned by John Suhler, founder and chairman emeritus of a private-equity firm, Veronis Suhler Stevenson, that specialized in investments in media and marketing businesses, and his wife, Charlotte. The couple bought it in 2000 for $8.9 million and spent millions renovating and enlarging it to its current size.

The house includes rooms with handmade decorative plaster on the walls and ceilings. It is stocked with French period furniture and has a 50-foot-long country kitchen with reclaimed barn beams as well as a curved wall of windows facing the water. The house is located on Long Neck Point Road, on a mile-long and half-mile wide peninsula jutting out into Long Island Sound, where some of Darien’s largest and most expensive homes can be found. On a clear day, the Manhattan skyline is visible.

Credit Suisse,

and his wife, Cornelia.

Median prices in Darien were up 23% in the second quarter, according to a market report by Halstead Property, compared with the same quarter a year earlier. They were also up in five of eight towns in lower Fairfield County.

The listing brokers of the Darien property are Janet Olmsted. Chris Merritt and Judi McCarty of Halstead Property.

—Josh Barbanel

Calvin Coolidge Slept Here: A Washington, D.C., Mansion With a Storied Past Asks $26 Million

A 36,470-square-foot Washington, D.C., mansion built by the daughter of newspaper publisher Joseph Medill is on the market for $26 million.

Located at Dupont Circle and called the Patterson Mansion, the four-story white marble and glazed terra cotta home on a 1/3 of an acre has 16 bedrooms, eight full bathrooms, seven half-baths, a grand ballroom with 14-foot ceilings, library, auditorium, an elevator and parking for 10 cars. The garage was the first enclosed garage in Washington, says listing agent Jonathan Taylor of TTR Sotheby’s International Realty in D.C. The house includes antique limestone fireplaces, crystal chandeliers, herringbone parquetry floors and historic tiger oak floors.

Mr. Medill’s daughter, “Nellie” Patterson, built the home from 1901 to 1903 with her husband, Robert Patterson, who was editor of the Chicago Tribune. According to Mr. Taylor, the Pattersons, who liked to entertain, worked with New York architect Stanford White to design social spaces on the first and second floors, with private living areas on the third floor. In the 1920s, Mrs. Patterson passed the property onto her daughter, “Cissy” Patterson, in her will. Cissy continued throwing parties and even offered the home to President Calvin Coolidge and his wife, who lived in the mansion during the summer of 1927, when the White House underwent renovations.

The seller is the Washington Club, a private social club, which is selling because it is disbanding and it no longer needs a big space, Mr. Taylor says. The Club purchased the property in 1951 from the American National Red Cross, which received the property in 1948 through Cissy Patterson’s will.

Mr. Taylor says a foundation or embassy most likely will be interested in the property as a headquarters. He shares the listing with Christopher Ritzert and Christie Weiss, also of TTR Sotheby’s International Realty.

—A.A.