Fostering fancy apartments. (dbox/Zeckendorf Holdings)

Those Zecekendorfs sure do love their starchitects.

From William Zeckendorf's work with I.M. Pei and Minoru Yamaski in the 1960s and '70s to his grandsons' projects with the likes of  KPF and, most notably, Robert A.M. Stern, who created both the brand new 15 Central Park West and the newly renovated 18 Gramercy Park South, the Zeckendorfs have a thing for high design.

Add to that now 50 UN Plaza, a 44-story condo tower on the East Side that will be Lord Norman Foster's first residential commission in the United States. Mr. Foster is well known for his work on the Hearst Tower, World Trade Center Tower 2 and the new Sperrone Westwater Gallery on the Bowery, as well as a new commission for 425 Park Avenue for L&L Holdings. With this latest commission, he cements his place as an all-around architectural power in the city.

Tomorrow morning, Arthur and William Lie Zeckendorf, real estate scions like few others, will break ground on the project at 345 East 46th Street, on the corner of First Avenue. The location will afford the project prime river views, as well as a prominent place on the skyline right between the United Nations headquarters and the Trump World Tower. The Observer has obtained an exclusive rendering of the project, which shows a glassy building of in the high-tech vein for which Foster + Partners is best known.

More demure than buildings like Hearst or the so-called Gerkin in London, 50 UN Plaza seems to strike the proper balance of brash understatement the Zeckendorf's so seem to favor.

The project holds special significance for the Zeckendorf family, since they got their start at the United Nations. William Zeckendorf, Sr., assembled the land that Nelson Rockefeller than bought to build the United Nations complex, and Arthur and William Lie Zeckendorf's maternal grandfather was Trygve Lie, who served as the first secretary general of the United Nations.

A special announcement of a gift to the neighboring Daag Hammarskjold Plaza park is expected at the ground breaking, with Borough President Scott Stringer in attendance, as well as local Councilman Dan Garodnick and Eyal Ofer, head of Global Holdings and a partner in both 50 UN Plaza and 18 Gramercy Park South.

The project will include 87 units, ranging from one-bedrooms as large as 1,100 square feet to three bedrooms as big as 3,000 square feet. There will also be a number of full-floor residences twice that size, as well as a penthouse duplex measuring some 10,000 square feet. Like at 15 Central Park West, one of the marquee features will be a private driveway. It is Lord Foster's first American apartment tower, following on the success of work he did in Vancouver, at Jameson House, completed in 2004.

The development of 50 UN Plaza is expected to cost $500 million to build, with completion by the end of 2014. If it is even close to the success of 15 Central Park West, which sold $2 million worth of units when it first came on the market (and is worth probably twice that now given a gangbuster market for resales in the famed building), then the Zeckendorfs and their partners should have no problem making an easy return on their investment here.

It looks like have just wrested the crown of New York's most luxurious development back from Gary Barnett.

Scott and Donya Bommer (Photo from Patrick McMullan)

Back in July, The Observer learned that William Lie Zeckendorf had found a buyer for his half of the old Wasserstein pad at 927 Fifth Avenue, which he had purchased for $29.1 million only seven months earlier. The purchase price was rumored to be as high as $34 million, well above the $31.5 million ask and a good explanation for why Mr. Zecekendorf might ever think of selling, given the quick turnaround. It turns out, the sale was even higher than that.

Plummeting stock market? Global recession on the horizon? Didn't seem to bother Scott Bommer, founder of uber hedge fund SAB Capital, and his wife, Donya. The Times revealed the couple as the buyer of the Zeckendorf pad, and they paid $34.6 million for it, meaning an extra $600,000 in Mr. Zeckendorf's pocket. There must be something about the apartment at 927 Fifth which begs buyers to unload their wallets, throwing in many millions of extra dollars to seal the deal. Remember, Mr. Zeckendorf paid well over the $26 million ask, as well.

Mr. Zeckendorf is no stranger to wise-if-often-eyebrow-raising real estate deals, of course. There was his record-setting sale at 15 Central Park West last December, raking in an extraordinary $30 million profit. For their part, Mr. and Mrs. Bommer are no newcomers to the world of luxury flips: they sold their Ritz pad for $3o million, according to The Times, after buying it three years prior for $28.5 million.

He's got a long way to get to enter William Lie territory.

Money slept here. (Haus Fitzgerald)

Could William Lie Zeckendorf be the shrewdest man in New York City real estate?

The only thing more surprising than the news just over a month ago that Mr. Zeckendorf was selling the top half of the late Bruce Wasserstein's old duplex at 927 Fifth Avenue—which he fought off a number of other buyers for in a madcap one-day auction—is that he found a buyer less than a week after putting it on the market. Not only that, but according to a number of sources, the five-bedroom spread went for "well over" its $31.5 million asking price after some zealous bidding. One broker said the price could even be in excess of $34 million.

This could help explain Mr. Zeckendorf's unexpected decision to sell.

As The Times noted 32 days ago, "brokers said the reasons for his selling again were unknown at this point." Well, now we may know, as Mr. Zeckendorf could be turning a $5 million profit on the five-bedroom home overlooking Central Park, which he closed on in December for $29.1 million. He never moved in.

That may not be nearly profitable as one of his other jaw-dropping deals, the record-breaking sale of the penthouse atop 15 Central Park West, which went for $40 million, or nearly $10,000 a square foot, or four times what Mr. Zeckendorf originally paid to crown the building he and his brother built with Robert A.M. Stern. Then again, he turned around 927 Fifth in all of six months, instead of two years. Never mind that Mr. Zecekendorf does not need the money, 15 Central Park West having been a success in and of itself after it grossed a staggering $2 billion, an amount matched only in magnitude by the outsized resales in the building.

If the sale is true, and the contract goes through, it belies the fact that, like Bid 'Em Up Bruce, as Wasserstein was known, Mr. Zeckendorf is simply a consummate dealmaker who cannot say no to a good offer. "Will clearly knows what he's doing," one broker said. "He's going to be a lucky son of a bitch, whatever he does."

The identity of the buyer remains unknown, and there is still the possibility the co-op board might not approve. For the kind of money on offer, it might be hard to say no, though. A rising tide and all that. Plus, this is one of the more lenient boards in a stringent city. "Financially, it is tight, but socially, it's easy," one broker said.

John Burger, Mr. Zeckendorf's broker, as well as his firm Brown Harris Stevens, which manages the building, declined to comment. Mr. Zeckendorf did not immediately return requests for comment.

If such numbers seem staggering—Wasserstein paid $15 million for both floors only a decade ago—brokers said it is an especially nice apartment in nearly perfect condition with not only views of the Park but also lots of light from the 74th Street side.

Completed in 1917 by Grand Central Terminal architects Warren & Whetmore, it is not the most distinguished of the Upper East Side co-ops. Nonetheless, it has attracted its fair share of notable owners, among them Mary Tyler Moore, Kenneth Cole, Richard Cohen and Paula Zahn and, perhaps most famously, the hawk Pale Male, whose perch was dislodged to widespread protest in 2004, until it was replaced three weeks later.

So quick turnarounds are nothing new in this building.

The view from up there, it's not what you'd think. (Patrick McMullan)

It was a bare-knuckled fight to get the home, as only there could be in New York, and now the buyer doesn't want it, as could only happen here.

Last year, half of the late Bruce Wasserstein's duplex at 927 Fifth went on the market. Brokers had all of one day to view the place ahead of a quick $26 million auction.

The winner was somewhat unexpected: William Lie Zeckendorf, who had been happily ensconced atop his own 15 Central Park West. Except that he would turn around and sell that apartment for a record-setting per-square-foot price of $40 million, leaving plenty leftover after he paid $29.1 million for the Wasserstein spread.

Maybe he missed the West Side or the finishes of his pal Robert Stern, because Mr. Zeckendorf has decided to re-list the home after only six months. It could hardly be called a flip, since the new asking price is $31.5 million. When the broker's commission, transfer taxes, and that onerous flip tax are factored in, the typically shrewd Mr. Zeckendorf actually stands to lose money on the deal.

According to The Times, the reason for Mr. Zeckendorf's departure from 927 Fifth remains a mystery. Maybe he's moving downtown like everybody else.

mchaban [at] observer.com | @MC_NYC

Part of the mystery surrounding the sale was who the buyer might be, and it's a surprising one. It's not your run-of-the-mill media mogul, master of the universe or movie sar.

The buyer of the 15 Central Park West penthouse was the co-founder of GPS pioneer Garmin, Min Kao, who still serves at the company's chairman and CEO. That's right, a global positioning system mogul--a very lucrative business it turns out, according to The Journal, which broke the news:

Mr. Kao, who was born and attended college in Taiwan, more recently has lived in the U.S., where he received his doctorate. Forbes last year estimated his net worth at $1.6 billion, down from $4.7 billion in 2007, following a decline in Garmin stock.

That's still enough money for a $40 million penthouse, which while not the most expensive residence ever sold in the city--not even last year, for that matter--still set the record on a per-square-foot basis.

mchaban [at] observer.com | @mc_nyo

Not only was it impossible to imagine Zeckendorf abandoning the best-selling building that he developed with his brother, but he also managed to break the limestone ceiling of $10,000-per-square-foot when he sold. (He left in part so that he might swoop into Bruce Wasersterin's old apartment). The per-square-foot price at the time was calculated at $10,259, a new record.

Well, the sale still holds the crown for the most expensive inches, but 15 Central Park West did not break the five-figure threshold, according to an article in The Journal this morning. Zeckendorf's 41st floor, 4,024-square-foot apartment only achieved $9,940-per-square-foot. So close!

But what is really startling is that the number of "trophy" sales, those above $30 million, continued to fall this year, from a peak of 21 such sales in 2008. Last year saw six, and there were 10 in 2007. The four trophies this year were only as many as changed hands in sleepy 2006.

While this may make sense, given the recession and the mediocre real estate market, it actually runs counter to much of the high-end market. The news of late has been the soaring success of expensive apartments, and that remains true. According to The Journal, sales between $10 million and $30 million rose 15 percent this year. Our pal Jonathan Miller told The Journal that this seems like a more normal sales pace, and the high number of super-high sales in 2007 and 2008 were "an anomoly."

mchaban [at] observer.com | @mc_nyo