NEW YORK (NYT NEWS SERVICE).- Over the years, architects have not been the only ones to inscribe New York’s skyline — the signature image of the last American century — across the urban ether.

Among others, structural engineers, practical poets of often towering imagination and import, have also figured out how to scale those heights. Skyscrapers are team efforts, after all. The insides of modern landmarks like Black Rock, historical monuments like the Statue of Liberty and some of the new supertalls now dwarfing yesterday’s cloud-scratchers are as eye-popping as what’s outside.

This is the latest in a series of diversionary walks around town — the second of two (condensed and edited) virtual strolls exploring midtown skyscrapers, with the Seagram Building as a starting point. The first was with Annabelle Selldorf, an architect. I undertook this one with Guy Nordenson, an engineer.

Nordenson is a professor at Princeton University and founded Guy Nordenson and Associates in 1997. He got his first job during the mid-70s as a draftsman in the Long Island City studio of sculptor Isamu Noguchi and architect/inventor Buckminster Fuller. He was the structural engineer for the National Museum of African American History and Culture in Washington and the Menil Drawing Institute in Houston, among other projects.

Nordenson proposed that we stop on Sixth Avenue and 52nd Street at the CBS Building, better known as Black Rock, the 1960s landmark by architect Eero Saarinen — then stroll past the former AT&T Building, the Postmodern confection with the Chippendale crown, now called 550 Madison Avenue, from 1984. We ended our walk at 432 Park, the super-skinny, supertall, super luxury apartment tower from 2015, teetering over 57th Street. Seagram, completed in 1958, is the landmark bronzed monolith poised serenely behind a pink granite podium between 52nd and 53rd Streets on Park Avenue. The building was commissioned by Samuel Bronfman, chairman of Seagram, the Canadian distillery. His daughter, Phyllis Lambert, picked the architects: the German-born Mies van der Rohe and Philip Johnson. Fred Severud was the structural engineer.

Michael Kimmelman: A cocktail of sensibilities went into Seagram’s design.

Guy Nordenson: At one point, Johnson had an idea that the building should rise out of a pool of water. Bronfman thought maybe there should be a bank branch, to add income. Johnson, Lambert and Mies acted like a trio, discussing everything, supporting each other, maintaining the integrity of the design. For me, Seagram is the most remarkable high-rise in New York. It epitomizes the relationships among creative talents that need to come together to make something architecturally remarkable happen.

Kimmelman: Lambert was a linchpin.

Nordenson: She was a young sculptor and had moved to Paris to study when her father sent her an image of a proposed tower by Charles Luckman.

Kimmelman: During the ’50s, Luckman and William Pereira designed LAX Airport and CBS Television City, among many other projects in Los Angeles.

Nordenson: Phyllis had another idea. She wrote back this long letter telling her father he needed to make a work of architecture of the same quality and excellence that he wanted his liquor to be. Bronfman was sensitive about this. He had been caught up in Prohibition. He wanted to communicate that his liquor business produced the best possible product. She argued the building had to convey that same sense of quality, so he asked her to come back from Paris to help run the project. She consulted with Eero Saarinen and Philip Johnson, whom she knew, and concluded that Mies was the right guy, then convinced her father, and the two of them convinced Mies to set up an office in New York. Then Sam Bronfman decided he wanted a bronze building.

Kimmelman: Whiskey-colored.

Nordenson: This was crucial. Bronze was novel — the idea that you would use bronze as opposed to aluminum or steel to make the mullions for the curtain wall. Mies made the mullions in the same I-beam shape as the steel structure inside the building. The I-beam had emerged in the 19th century, out of the railway industry, and became standard for construction of tall structures because it uses steel efficiently. Mies adopted the shape for Seagram’s mullions, which adds this amazing, subtle depth to the curtain wall — a kind of ghostlike plane, in front of the plane of glass, which creates sharp black shadows when the sun is moving along the facade.

Kimmelman: Mies aestheticized the building’s deep structure.

Nordenson: The I-beam represented the industrial age but these bronze mullions are all bespoke products. The bronzed glass was specially produced by a small manufacturer in Pennsylvania. Seagram represents this wonderful combination of industrialization and craft, which I think is in dialogue with the craft of the Racquet & Tennis Club across Park Avenue, designed by McKim, Mead & White.

Kimmelman: From 1916.

Nordenson: Architecturally, there’s a very New York conversation going on that involves the role of wealth, the latest available technology and artisanship.

Kimmelman: We haven’t talked about Severud, Seagram’s engineer.

Nordenson: The most creative engineer of his time. He was working with Saarinen on the Ingalls Rink, called the Whale, at Yale, then he engineered the Gateway Arch in St. Louis. He was a big influence worldwide, a pioneer in the use of tensile structures.

Kimmelman: He did the Haus der Kulturen der Welt in Berlin, another curvilinear, sculptural structure. Among those, Seagram is the outlier.

Nordenson: That’s interesting. Seagram involved a very standard New York structure, similar to what was used 50 years earlier for the Woolworth Building by its engineer, Gunvald Aus, to accommodate the increased demand of the wind as you go from the top of the building down to the bottom. You know, the force of wind on a building accumulates as you get closer to the ground, so a structure like Seagram needed to be different at the top, middle and bottom, something that is not in any way visible from the outside, in the geometry of the architecture.

Kimmelman: I recall Mies having said, “whenever technology reaches its real fulfillment, it transcends into architecture.”

Nordenson: I agree. Phyllis Lambert makes the point in a book she wrote about the Seagram Building that the towers Mies designed in Chicago with another important engineer, Frank Kornacker, were very flexible. She lived on the top floor of one of those buildings and said she could feel the building move in the wind and saw cracks in the plaster walls. Flexibility is a choice, not strictly controlled by regulations. Normally, office buildings are more flexible than apartment buildings because it’s one thing when you’re sitting at a desk and walking around an office and a building moves, another if you’re lying in bed. This is why office buildings in New York tend to be made from steel, and very tall apartment buildings like 432 Park, which we will get to, are made of concrete. The concrete makes the building more massive, meaning less inclined to move when the wind blows because there’s more inertia.

In the case of Seagram, Fred Severud said there was no way he was going to allow the building to move like those Mies buildings in Chicago. He wanted a really, really stiff structure. So he also added a column inside the core, which he made Mies agree to.

Kimmelman: Guy, I can’t call this a “walk” if we never move.

Nordenson: Let’s look at Black Rock.

Kimmelman: From 1964.

Nordenson: Like Seagram, a monolith. Eero Saarinen was the architect. Next generation after Mies. Paul Weidlinger was the engineer.

Kimmelman: You used to work for Weidlinger.

Nordenson: Thanks to Noguchi, who was a friend of my mother’s. When I was in college, trying to figure out what to do with my life, Noguchi was the one who said to me, “You should be an engineer.” I didn’t think so. I was studying literature and philosophy. But then he brought me to work in his studio — this was 1975, ’76 — with Bucky Fuller, an architect working with structures in a creative, broad way.

I remember one New Year’s Day, working in the studio, mentioning to Noguchi that I was interested in meeting I.M. Pei. He picked up the phone and of course I.M. was sitting in his office, also working on New Year’s Day. So we drove there in Noguchi’s yellow VW station wagon. I tried to be a little mouse while they talked. I realized how much they appreciated each other’s work, how they shared a culture, across disciplines. Noguchi introduced me to Weidlinger.

Kimmelman: What was Weidlinger’s significance at Black Rock?

Nordenson: There was a preoccupation in the ’60s among structural engineers with developing a strategy for constructing extremely tall buildings, which led to the Sears and Hancock towers in Chicago and the Twin Towers in New York. Structurally, Black Rock is an important precursor to the Twin Towers. Like the towers, it spaces columns on the outside, very close together, which produces a cage-like perimeter that efficiently resists wind.

William Paley, who ran CBS, was the client for Black Rock, a very forceful character. I think, in the same way Seagram expressed what Bronfman intended about his liquor company, Black Rock expresses the authority Paley believed CBS commanded, as the network standing behind Walter Cronkite during the Kennedy assassination and the space program.

Kimmelman: Authority takes different forms. Philip Johnson, with his partner John Burgee, cooked up what’s now called 550 Madison for AT&T. The weighty granite facade, the towering, pulled-taffy proportions and supersized Italianate portico were all meant to project AT&T’s heft and permanence. Then the building opened in the midst of the telephone company’s breakup.

Nordenson: People don’t realize hiding inside that Chippendale exterior is a remarkable structure by Leslie Robertson, our greatest living structural engineer, who was the engineer of the Twin Towers. He’s creative in a way comparable to Eiffel. As you know, Gustave Eiffel’s structure for the Statue of Liberty suspends Frédéric Auguste Bartholdi’s copper sculpture from a central spine, much like the construction of a sailboat. Robertson does something similar here. Basically the way the AT&T Building works is that there is a spine going up the building that is the core, stiffened with steel plate and diagonal bracing to parry the majority of the forces due to the wind. In addition to that, there is a horizontal truss at the top of the building, and that ties the central spine to the columns of the building.

In essence, the building is like a sailboat, where you have a mast up the center, and then you have outriggers tied by cables to the hull of the boat, so when the wind blows, the outriggers and stays stiffen the mast. It’s an incredibly efficient and elegant way of stabilizing the building.

Kimmelman: Invisible from the outside. I play the piano and I know how certain things, which an audience may not focus on, are meaningful to pianists, because they know what went into them.

Nordenson: To me Robertson is a virtuoso.

Kimmelman: Detractors think the building is jokey because of the Chippendale top.

Nordenson: The best jokes require craft.

Kimmelman: You wanted to end with 432 Park Avenue, which always looks to me like an extruded Sol LeWitt sculpture. Rafael Viñoly was the architect, Harry Macklowe, the developer.

Nordenson: I watched the building go up from the window of my apartment. Ahmad Rahimian, from a firm called WSP, is the very talented structural engineer. He also did One World Trade Center with David Childs from Skidmore, Owings & Merrill and the Shard in London with Renzo Piano. In this case, the exterior is a gridded structure. All squares, with floor-to-floor heights represented in the spacing of the columns and beams — the grid made of exposed concrete, which is not common in New York, because the weather isn’t kind to exposed concrete unless it has been made very carefully.

You notice with 432 how some floors of the buildings are open spaces that let the wind pass straight through. Rahimian picked up on something Bill Baker from SOM came up with. Baker is another genius engineer. He engineered the world’s tallest building, in Dubai, the Burj Khalifa, and he also came up with a very beautiful scheme for a tower in Chicago that was not built but was going to be extremely tall. Baker devised a series of gaps along the height. He said the idea was to “confuse the wind.”

With very, very tall, skinny buildings, like 432, under certain circumstances when wind blows past them, little vortices form on the back side and detach at regular intervals. The phenomenon is called vortex shedding. It’s what brought down the Tacoma Narrows Bridge in 1940. Baker realized that a series of gaps along the height introduce turbulence into the flow of the air passing by the buildings that make it harder for the vortices to form — they confuse the wind.

Kimmelman: The building still moves, of course. Baker once said to me that for the people who live in a supertall luxury apartment tower like 432 Park, the movement just can’t disturb a champagne glass on a dining table.

Nordenson: The champagne can move, but not the glass. It won’t bother the occupants if the movement is gradual. Towers also employ dampers. There are giant pendulum dampers and sloshing dampers, which are basically tanks filled with water. The water sloshes from one tank to another, in the direction opposite the one in which the wind is moving the building.

Kimmelman: I believe 432 has twin dampers, the size of locomotive engines.

Nordenson: Like with opera or film, architecture involves all these myriad parts and different talents, many of which go unnoticed. I think New Yorkers are appreciating the variety and depth of talent that’s required to get through a crisis like the pandemic — how many different people play essential roles, people not always recognized.

Kimmelman: We have a lot of people to thank.

Nordenson: It’s the same with great buildings.

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