At the sales gallery launch, Rosen said he first asked Norman Foster (who was not in attendance) if he had the “balls to do this.” Foster did: the 63-story tower directly abuts the Seagram Building and hovers more than 20 stories above it. The skyscraper (which used the air rights from the Seagram) is set to top out by the end of the year and is on track for completion in 2017.

According to Peter Han of Foster + Partner’s New York office, the challenge was to arrive at the proper proportions—respecting and responding to the Mies-designed building, while making a statement.

Said Han, “The overall experience, I hope, is innovative and intuitive.”

In the spirit of its International-style neighbors (SOM’s Lever House is just one block away), the architects sought to keep the new tower minimal. The building’s faceted facade, clad in white metal panels to contrast the black Seagram, is intended to make the form appear slender—an effect Han described as “powerful, yet graceful” and “restrained, yet elegant.”

Foster + Partners also designed the residential interiors (William T. Georgis is designing the amenity spaces and lobby). The spare concrete rooms, with ribbed ceilings and track lighting, recall the style of Tadao Ando and are catered to an art-collecting clientele. To drive this point home, the sales showroom was hung with a Basquiat and a Twombly.

In addition to the 96 swanky residences (beginning at $3.5 million), 100 East 53rd Street will include a two-story market and food hall (think Eataly), and a to-be-named three-star restaurant, which Rosen guaranteed will have “really yummy food.”

The building is a part of Rosen’s efforts to usher the block into a new golden age, perhaps a graham cracker-golden one, to borrow the parlance of the New Yorker in its profile on Rosen. The developer signed a deal this summer with chefs Mario Carbone and Rich Torrisi of Carbone and Dirty French, to replace the Four Seasons Restaurant next door.

At best, these efforts have been controversial, especially when it comes to the Seagram Building and it’s landmarked interiors: Rosen ignited outrage when he removed a fragile Picasso tapestry from a main passage last year. He further ruffled feathers when he raised the famed eatery’s rent five-fold, compelling it to pack its bags next summer. Most contentious of all, he enlisted architect Annabelle Selldorf to overhaul the modernist Philip Johnson-designed dining rooms. While the preservationists ultimately got their way at a Landmarks and Preservation Commission hearing in May (a change in carpet color was approved), they are wary of how the new Foster + Partners tower will affect the architectural integrity of the block.

But Rosen seemed keen to create a hot fuss: “100 East 53rd Street" has a lot of energy, and that’s exactly what we want to deliver.”

For more information about 100 East 53rd Street, click here.