At least one and possibly all five towers at the massive Riverside Center development will not be the work of Pritzker Prize-winning architect Christian de Portzamparc. The French designer helped Extell Development and the Carlyle Group sell their swank plans' to the community and the City Planning Commission. The latter was so taken with the crystalline designs of Mr. de Portzamparc, who also designed the LVMH headquarters and Extell's One57 tower, that restrictive zoning covenants were set to ensure the buildings would look as promised.

But now, Extell and Carlyle have turned over one of their tower sites to the Dermot Company, which has hired local firm SLCE to design the apartment building on the West End Avenue section of the site. While Dermot insists its project will be up to the standards promised during last year's public review process, some, including the exacting City Planning chair Amanda Burden, worry the design doppelgangers will lead to lesser work.

“I am extremely disappointed to learn that the developer of Riverside Center has chosen not to retain Christian de Portzamparc as architect for this project," Ms. Burden said in a statement.

When Dermot came to the local community board last month to present its version of the designs, there was some disappointment that they had not been joined by Mr. de Portzamparc. "If you look at it, they're more usual, they've probably been value-engineered," Ehtel Shefer, chair of the board's Riverside Center working group, told The Observer in a phone interview. "I don't know if it's the feeling of the entire board, but certainly some people were disappointed."

Back in 2005, Carlyle and Extell bought the remaining undeveloped portion of Donald Trump's Riverside South development from his Hong Kong partners (to the consternation of Mr. Trump) for $1.76 million. Much of it has since been developed as new towers by Gary Barnett, Extell's principal, but the southernmost parcel had to be rezoned because previous plans called for a new television studio to be built on the site.

Instead, Mr. Barnett trotted out his plan for a 3.1-million-square-foot city within a city within a city designed by Mr. de Portzamparc. Five jagged towers were arrayed around three acres of open space. After much back-and-forth with Councilwoman Gail Brewer, the developers agreed to building 20 percent of the apartments as affordable housing and to include a school on the site.

When it came time to start building, Carlyle, which controls a majority stake in the site, decided to hold a competitive bidding process, to which Extell was invited but not guaranteed the chance to build the first tower. Instead, the prize went to Dermot. When it comes time to build the remaining four parcels, Carlyle expects to go through the same private bidding process.

Mr. Barnett said that given the large amount of affordable housing and the school in the first building, he was less interested in winning the project. He still hopes to take the lead on some, if not all, of the other development sites, though he acknowledged there was no guarantee any of the towers would be his to build.

"I hope we get to build some, but I don't know," he said. "If we do, I can tell you, Christian de Portzamparc will be our architect."

Carlyle declined to comment.

Councilwoman Brewer was ambivalent about the changes. "I was more concerned with the school and the affordable housing, but I can see why people might be angry about this," she said, adding that of Mr. de Portzamparc, "They certainly made a hard sell for him during the ULURP."

In a brief statement, Dermot principal and COO Stephen Benjamin, stressed that his tower was still under design and, given the zoning covenants, would still resemble what was originally proposed. “We are in the midst of the design process for a spectacular building that will be in full compliance with the zoning as is our obligation and right," Mr. Benjamin said.

Ms. Burden raised the same point in her statement, that even if the de Portzamparc name is not on the final buildings, his master plan for the site remains, and the essence of his work will persist.

"The integrity of de Portzamparc’s work will be maintained because key architectural features—including, among others, building silhouettes, distinctive sloped and angled sculptural  forms, facets and sloping tower tops—are embodied in the land use approval and are a condition of developing the site," Ms. Burden said. "De Portzamparc was instrumental not only in shaping the site but also in developing these design controls."

"The City Planning Commission fully understands that a developer may decide to change architects over time for a number of reasons," she continued. "De Portzamparc’s important contribution to this project will survive this developer’s decision to look elsewhere for design services."

This is not to suggest that SLCE is necessarily a worse choice as the project's architects, either. In fact, the firm is frequently brought on by developers to serve as the architect of record for more highfalutin designers like Mr. de Portzamparc.

The globetrotting architects (Gehry, Nouvel,Koolhaas and the rest of the designer jetset) are not usually experienced in the intricacies of jurisdictional buildings codes, idealized layouts and local tastes. It falls to firms like SLCE and Goldstein Hill & West—which has also done extensive work at Riverside Center and may well wind up designing some of these tower—to bring a strarchitect's dream into the realm of the buildable, the inhabitable, the comfortable.

That said, some connoisseur's counter that these firms' work can be pedestrian and developer-driven, lacking the flair of some of their more renowned rivals.

Neither is this switcheroo exactly new. That is a big part of the reason the City Planning Commission works so hard to ensure certain design flourishes and details in ambitious projects like the Riverside Center.

Mexican master Enrique Norten was originally pitched as the architect of the Edge condominium towers on the Williamsburg waterfront, only to be swapped out for Stephen P. Jacobs and Associates when it came time to build. Richard Meier and SOM came up with the scheme for Sheldon Solow's Con Edison development just south of the United Nations. Parcels have since been sold off, with more on the block, and it is uncertain who might wind up conceiving of the final projects.

Most famously, Bruce Ratner dumped Frank Gehry from his Atlantic Yards project after the recession led to a reevalution of the work of the Pritzker Prize winner, whose buildings are notoriously expensive and difficult to execute. Mr. Ratner tapped Ellerbe Beckett, a no-nonsense designer of sports venues throughout the nation, to replace Mr. Gehry on the Barclays Center. Even though she had no oversight of the project at any point, Ms. Burden was said to be so bothered by the switch that she successfully lobbied to have local wunderkinds SHoP brought on to help redesign the facilities.

The most apt comparison to the situation at Riverside Center might be what happened at the World Trade Center. Little remains of Daniel Libeksind's masterplan but the outlines of the project, a crescent of towers stepping down in size along Greenwich Street. Granted, some of the world's most famous architects have stepped in to replace Mr. Libeskind. At the same time, the strict design controls at Riverside Center will make any successors who are not Mr. de Portzamparc stick much closer to the French architect's vision.

Ms. Sheffer points to an incident closer to home, Fordham University. The school was working on plans to redevelop its Manhattan campus near Lincoln Center, which included selling off some parcels for development. While there was a general consensus that a residential tower proposed by Douglaston Development was too big, people at least seemed to like the design created by celebrated architect Cesar Pelli, he of World Financial Center and Bloomberg tower fame.

"The deal seemed to be the deal," Ms. Sheffer said of Fordham's plan, "but then they made a deal with Glenwood, and suddenly it looks like everything else Glenwood has done and that's not every interesting."

She hopes this will not be the case at Riverside Center. "I think the feeling was, the de Portzamparc buildings, it was a vision, a particular kind of towers that related to each other and to the open space and the neighborhood, with the view down to the river," Ms. Sheffer said. "In the renderings, it certainly didn't look like the rest of Riverside South, and that was a good thing. But now, we can't be so sure. Maybe it's a lot of hype, maybe not."

But would this be New York City real estate if that were not the case?

Update: This story has been changed to include details about other projects that have gone through similar design switches as well as other projects SLCE has worked on. Also, a previous version stated that Dermot was developing two towers on the site, rather than just one. The Observer regrets the error.

The entrance to the new tower. (DNAinfo)

The Christian de Portzamparc project is at the northwest corner of the site. (DNAinfo)

We already know that the DMZ between the Upper West Side and Hell's Kitchen (call it Lower West End Avenue?) is a happening spot, with the Walentases, the Dursts, the Elghanyans, basically everybody building a slick new project over there. The biggest, of course, is Riverside Center, Gary Barnett's massive reimagining of the final plots of the Riverside South complex.

Earlier this week, Extell returned to the local community board with plans for affordable housing in the project, according to DNAinfo, and therein he revealed the latest detailed designs for the Christian de Portzamparc-created project.

Construction at Riverside Center is expected to start on the first tower, known as Building 2, at the corner of Riverside Drive and West 61st Street, in November, pending city approval.

This particular project is Building 2 in this diagram. (DNAinfo)

Twenty percent of the building's 616 units are slated to be affordable, ranging between $529 for a studio and $1,009 for a three-bedroom apartment. Qualifying families must earn between 40 and 50 percent of the annual median income in the city, which is between $23,000 and $43,000, depending on household size.

The board generally looked favorably on the project, though, naturally, there were calls for even more affordable housing.

Update: The project is actually being developed by the Dermot Company and designed by SLCE, not Mr. Barnett and Mr. de Portzamparc. The parcel for building 2 has been sold off to the former firm following a public approval process involving the latter—where the public quite liked the work of Mr. de Portzamparc. Now that he has been switched out, it will be curious to see what people think.

Whoa, oh, here she comes. (Elevator View)

Someday soon? (ACdP)

Our pal Elevator View (one of the best photo tweeters/bloggers in town) shot us this photo of new construction fencing going up at 400 Park Avenue South, suggesting that Christian de Portzamparc's long-delayed crystalline apartment building will finally rise there starting this year.

Almost a decade in the works, the project was left for dead in the doldrums of the recession until Toll Brothers and Sam Zell decided to team up this spring to take on the project. According to public records, building permits were approved between April and June, so the 42-story tower, with 363 units, is ready to rise. Neither of the developers were immediately reachable.

We spotted only one penthouse, up on the 40th floor, according to the Schedule A, but there was this one fun tidbit down in the basement: FITNESS CENTER, LAP POOL, YOGA ROOM, KIDS ROOM, LOUNG/CLUB ROOM, THEATRE, GOLF ROOM.

This not only looks like but really is the Fortress of Solitude—it has everything!

Updating Park Avenue: an early conceptual rendering by L&L of the potential for 425 Park. Might these designers do them one better? (ll-holding.com)

It is one of the stranger developments in the city, but it could also prove to be one of the most spectacular. David Levinson is poised to tear down most, but not all, of 425 Park Avenue—were he to totally demolish the tower, what he could replace it with could be quite a bit smaller, given a quirk in the 1961 zoning that reduced the density of the site, where a rather unremarkable and outdated 1958 tower now stands.

To fix this problem, L&L Holdings, Mr. Levinson's development firm, tapped 11 of the planets top architects to sort out this challenge. He has now winnowed the designers for 425 Park down to four, according to The Times, with an unveiling expected shortly. All of them are Pritzker Prize winners with a mixed history in the city.

Only Lord Norman Foster has enjoyed real success here, with his Hearst Tower and Sperone Westwater gallery on the Bowery. His fellow Brit Sir Richard Rogers has had a number of almost-built projects, from Vornado's Port Authority tower to a vastly expanded Javits convention center. Both are also working on nascent towers for Larry Silverstein at the World Trade Center. Then there is Rem Koolhaas, who despite making his name here with the book Delirious New York, has only ever built a store for Prada, and Zaha Hadid. The first woman to win a Pritzker Prize (along with her three competitors), she has only one American project to her name, the Cincinnati's Contemporary Arts Center.

The six designers who did not make the cut have all built quite a bit here: Christian de Portzamparc, Herzog & de Meuron, Jean Nouvel, KPF, Fumihiko Maki, Renzo Piano and Richard Meier.

Whomever should win, this project has the possibility to present the city with a new, daring landmark. That is if David Levinson will allow it. As The Times notes, a prospectus for the project warns the four designers not to be too indulgent: "While the client team is open-minded about material and aesthetic expression, a restrained elegance has often proven to be more successful for this building type than irrational exuberance.”

This is presuming, of course, he does not get carte blanche to design any kind of building, courtesy of the big Midtown East rezoning.

Hello, my pet. (one57.com)

We already know One57, like all of Gary Barnett's projects, is the best everything all the time.

This goes for its marketing materials, too. Get a load of this insane video, for example, just posted to the development's sleekly updated and expandedsite. Herein some clever video editors make Christian de Portzamparc's tower come alive, which we guess is the kind of industrial light and magic one can afford when a project is on pace to gross $2 billion.

In the video, the Pritzker Prize-winning Frenchman reveals that tall buildings in Manhattan give him "pleasure." He rhapsodizes in his adorable accent about the changing perceptions of the tower from every angle. "This is not an abstract thing like an office tower," Mr, de Portzamparc says. "This is dwellings."

To that end, "every dwelling has its own glass, its  own color. And this creates a Klimt effect, which indicates that you have different glasses for the window reflecting differently the sky."

Maybe Ron Lauder should buy an apartment.

"This is changing the skyline of Manhattan," he concludes, looking like Godzilla about to smash his creation, "changing the landscape. This contribution here is one gesture, which will be important."

The real gesture is the video, which if we have not made it clear by now, you really must go watch.

While working on yesterday's story about Christian de Portzamparc's decade-long struggle to get his tower at 400 Park Avenue South built, we stumbled upon another striking New York project by  the Pritzker Prize-winning Frenchman that never was. For two years starting in 2004, Mr. de Portzamparc labored on a new home for the New York City Opera, to be built on a site that belonged to the American Red Cross, before the dream was shattered like the climax of an opera.

The project is poignant for a number of reasons. It was developed by A & R Kalimian, the same firm responsible for 400 Park Avenue South. When the plan fell through, the opera continued to hunt for a new home, only finding  one this year at BAM in Brooklyn, far from Lincoln Center. And this was only after a labor dispute nearly shut the whole show down for good. And the unusual appeal of New York to Mr. de Portzamparc—not unlike his countryman Jean Nouvel—cannot be ignored.

This video of the project shows just how daring, if ill-fated, New York's cultural projects can be. It is strange that whomever made it chose a techno track to back it, though.

mchaban [at] observer.com | @MC_NYC

That was Andre Terzibachian's response when The Observer emailed him about 400 Park Avenue South on Friday. A partner at Atelier Christian de Portzamparc, Mr. Terzibachian is responsible for many of the firm's projects in New York, where the Pritzker Prize-winning Frenchman has had a number of surprising successes: the jagged LVMH North American headquarters on 57th Street; the skyline-redefining, outrageously priced One57 now rising a few blocks to the west; and beyond that, abutting the Hudson River, a daring complex of five towers at Riverside South.

All the while, 400 Park Avenue South was in the works the middle of Manhattan as a small-time developer tried, and eventually failed, to get an ambitious project off the ground. (Oddly enough, it is the only of Mr. de Portzamparc's projects not somewhere on 57th Street.) Construction was set to begin after years of development and zoning approvals. Then the recession hit. In December, the site was sold to a partnership of two of the nation's biggest builders, Toll Brothers and Sam Zell's Equity Residential. It was not clear at the time what the fate of this crystalline castle would be, but it turns out Mr. de Portzamparc will be planting another shard in the New York skyline after all.

On February 3, Handel Architects filed a slew of new construction documents for a 42-story residential tower at 400 Park Avenue South with the Department of Buildings. Handel had been the architect of record for de Portzamparc's earlier project (most out-of-town designers must team up with a local firm to file construction documents on its behalf), so it seemed promising that the eagerly anticipated tower would soon rise. David Von Spreckelsen, a senior vice president at Toll and head of its New York office, confirmed that Mr. de Portzamparc was indeed on board for the project. He is still designing the facade, as had originally been planned, a design that has not changed much, for reasons both aesthetic and practical.

The new team did not want a "Joe Blow building," as Mr. Von Spreckelsen put it. But there was also the fact that the previous developers went to so much trouble getting their project designed and then approved by the city. To switch architects and do it all over again would probably have been more expensive than simply adopting Mr. de Portzamparc's progressive designs for the tower at the corner of 28th Street. "If we wanted to abandon that design, we could have actually built something much taller, but it was a sort of pencil building going straight up," Mr. Von Spreckelsen said. "At the end of the day, it was too inefficient, because too much of it would have been taken up by the core. You weren't going to have the living space on the floors."

There will be one small alteration to the design, using a different type of glass that offers greater energy efficiency, a nod to the recently passed green building codes, but otherwise the tower will look almost exactly the same.

Keeping the same architects also meant the project could start almost immediately. "The documents were (almost completely) ready since we were supposed to deposit the building permit a few years ago, so we were able with Handel to get things done rapidly," Mr. Terzibachian wrote in his email. Groundbreaking is set to commence in May, Mr. Von Spreckelsen said, with an expected completion by the end of 2014.

Mr. Von Spreckelsen said Toll Brothers was especially excited about the project because of the unique arrangement it had reached with Equity Residential, whereby the latter is building rentals on the bottom half of the building while the former builds condos on the 20 floors on top. "They're taking the first 22 floors, so our condo units are starting at 250 feet in the air, so every unit has a pretty great view," Mr. Von Spreckelsen said.

And the unique design should appeal not only to those living inside the building.

"It's obviously really going to change the way Park Avenue South looks," Mr. Von Spreckelsen said. "I know that it's one of Christian's favorite buildings he's ever designed, and I know the city administration loves it, so I think it's going to be great for everyone."

mchaban [at] observer.com | @MC_NYC

Skyline, here we come! (Matt Chaban)

Leaving the Building Congress luncheon today, The Observer looked up to notice something we had never seen on the Midtown skyline before: One57! Garry Barnett's Central Park-towering apartment building is now totally a part of the city skyline, unavoidably peeking down on Columbus Circle.

Wavy gravy. (Curbed)

It will only continue to grow, inexorably, until the multimillion-dollar foreigners can move in, pushing the rest of us out to the Rockaways.

This is not the only interesting look we've gotten of the building lately. Just last week, Curbed noticed that some very funky glass panels had arrived at the base of the cloudbusting building, as well. This thing is going to be finished, and glorious, before we all know it.

mchaban [at] observer.com | @MC_NYC

As Extell's One57 climbs skyward, so do the prices, with the penthouse now asking an astronomic $110 million. Christian de Portzamparc, the Pritzker Prize-winning architect behind the project, discussed the inspiration for the tallest residential tower in the city with the International Business Times, where he revealed new details about the project as well as (and more importantly) new renderings.

It is ironic that with all the griping about New York's construction constraints, Mr. de Portzamparc said he found the city liberating. "In fact, New York is very attractive," he said. "There are fewer constraints than in most of our European cities." He told the IBT that the building is a tribute to Central Park, of which it will have commanding views, as well as the skyline itself, where the new tower will "evoke the energetic cascade of New York's verticality."

He also believes architecture can do more than it does for humanity and society. "We need to rediscover the essence of the meaning of 'the use,'" Mr. de Portzamparc said. "Architecture is above all here for a better living. Every gesture, every shape must be justified by various reasons that would reinforce their reason to be, their use, and will give more sense to their beauty."

What does Rafael Viñoly have to say to that?

mchaban [at] observer.com | @MC_NYC

Worth it? (Extell)

Sales opened today for Extell's giant glass tower, One57, the latest and greatest in Midtown developments. When completed, the building will stand 90 full stories (no, that's not a typo), and will be topped with a $98 million penthouse. The building, which will also include a "Five Star" Hyatt hotel (seems to be "five star" in the abstract adjectival sense, seeing as construction isn't even complete yet...), in addition to the 95 luxury condos which can be yours, all yours, starting at just $6.375 million. Any takers? OK, aside from foreigners?

Christian de Portzamparc designed the building's facade, which looks like a toned-down Hyatt-y version of Gehry's "New York." The interiors of the condos were designed by Thomas Juul-Hansen who "took inspiration from de Portzamparc’s exterior, creating discreetly opulent interiors with a nod to French modernists such as Jean Michel Frank," according to a press release.

An updated website also features an exorbitant 360 panorama of these one-of-a-kind, Empire-State-Building-worthy views and a video of how Mr. de Portzamparc conceived of such a colossal tower.

And so you are now one step closer to getting that $98 million penthouse you've always wanted! Christmas present?