Baker in front of Manhattan's Marine Midland Bank Building, built by his firm in 1967. *

Photo: Kevin Cooley * Seventy feet beneath the Las Vegas strip, in a construction pit that will become the Cosmopolitan Resort and Casino, Bill Baker is looking for local talent. Baker is the head structural engineer at Skidmore, Owings and Merrill, the famed building design firm responsible for the Sears Tower in Chicago, the Time Warner Center in New York, and scores of other colossal glass boxes across the globe. This morning he's wearing a hard hat and an orange safety vest as he watches a Nevada construction crew at work. He'll likely draft some of them for his next big project, the multibillion-dollar Crown Las Vegas Resort and Casino. At 1,888 (lucky) feet, it will feature what could be the world's highest gaming room, 142 stories above the desert floor. Provided, that is, the Federal Aviation Administration will let it scrape the skies so close to the airport.

Baker inspects welds with his fingertips and, not one to suffer waste (even in Vegas), he looks appraisingly at the oversize columns. Then he rests a dusty dress shoe on a pile of rebar and turns to Brian Calley, an engineer at Schuff Steel, with the question that got him up early this morning, a question that's key to making the steel-framed Crown a reality: "So, what's the biggest thing you're working with?" The Crown will use around 72,000 tons of steel, and Baker needs to know that Schuff can handle that kind of metal. At Calley's answer (16 feet wide by 60 feet long), the bespectacled Baker enthusiastically sticks two thumbs up in the air. The fewer pieces you have to pick up and connect, the faster the building rises. And Baker knows that speed and efficiency will be just as important to getting the Crown off the sketch pad as the schematic itself. "Erection is everything," he explains. The problem with most ambitious architectural endeavors is that "people don't figure out the right way to build them when they design them."

It's this mind for efficiency that has made the practical Missourian the most important structural engineer in the world. More than the notable projects he has already built — from skyscrapers like the 73-story Tower Palace III in Seoul to the Frank Gehry designed bridge at Millennium Park in Chicago — Baker's main contribution has been a completely novel way of constructing them. Dubbed the buttressed core, it works like this: Three structural "wings" extend out of a central hub. The wings provide support for the building, and the core keeps the wings firmly anchored so they don't twist in the wind. The design allows Baker's buildings to go up tall, fast, and with enough usable floor space to maximize his client's chances of turning a profit. "It's not just that Bill is a brilliant engineer — which his buildings are demonstrating," says Carol Willis, director of the Skyscraper Museum in New York City. "He's posing new structural approaches rather than reworking old ones, and that's what it takes to build something unprecedented."

Baker's current slate of supertalls — towers that exceed 1,000 feet — is unmatched by any engineer in history. It surpasses even SOM's own record from the late '60s and early '70s, when the firm built the 1,450-foot-tall Sears Tower and the 1,127-foot-tall John Hancock Center within a few years (and 2 miles) of each other. There's the Crown here in Las Vegas; the 1,361-foot Trump International Hotel and Tower in Chicago; the 1,820-foot Lotte Super Tower in Seoul, to be completed in 2012; and the queen of them all, the Burj Dubai, in the United Arab Emirates. It's a fantastic spike of a building — soon to be the most desirable address in the Middle East, already the tallest structure of any kind and still rising by a floor every three days to a top-secret height of at least 2,500 feet — more than double the size of the Empire State.

Baker's ascension — and his buttressed core — comes at the beginning of the supertall era. People, corporations, and even desert city-states with oversize checkbooks and matching egos are racing to conquer their skylines. Most of them call Bill Baker.

Since its founding in 1936, SOM has been the court architect of the global corporation, designing and engineering hundreds of glass-and-steel towers for business districts the world over. For nearly 25 years, it held the crown for the tallest of the tall — until 1998, when the Petronas Towers (1,483 feet) in Kuala Lumpur, Malaysia, squeaked past the Sears by the height of its twin spires.

The '80s and '90s were lean years for supertalls, but Baker never stopped "thinking the problem," to use his favorite phrase. On weekdays, he'd diligently execute his duties as an associate, crunching numbers and working on small aspects of larger projects for the senior engineers. But he spent his Saturdays at the Illinois Institute of Technology — the MIT Media Lab of the tall-building world — studying with his mentor, Myron Goldsmith. Goldsmith had helped develop some structural systems: the tubular, used in the World Trade Center and the John Hancock Center, and its successor, the bundled tube, used in the Sears Tower. Together, Goldsmith and Baker studied old supertall schemes and hatched new ones to test their ideas.

Baker rose through the engineering ranks at SOM with a triple threat of skills — uncommon creativity, mathematical mastery, and a quiet salesperson's flair. He may wear the SOM uniform of a jet-black suit — crisp, elegant, unadorned — but his inner nerd is still easy to spot. Looking like William Hurt with Coke-bottle glasses, Baker carries his paperback-sized HP 48gx graphing calculator everywhere, usually stacked on top of a beat-up Moleskine notebook filled with pencil drawings and formulas. While his architect colleagues may get more of the media spotlight, Baker goes along to pitch clients — just to make sure everyone knows that SOM's fancy skin comes with the best bones.

On a summer afternoon, sitting in a conference room overlooking a thicket of downtown Manhattan towers, Baker lays out "the tall-building problem": Stay small, and structure is cheap. But go tall, and a major percentage of your cost goes to a larger and larger framework, just to make sure the thing doesn't topple over. "And sometimes," Baker says, "that becomes a hurdle you can't get over."

Photo: Getty ImagesPunching buttons on his calculator, Baker runs the numbers. "The cost per square foot goes up by somewhere between the square and the cube of the height," he says glumly. "Basically, if you keep the same footprint and make a building twice as tall, the cost of every square foot becomes somewhere between four and eight times as much." So while someday the height of a building will be limited by the eardrum-rupturing pressure changes in its fast-moving elevators, the current restrictions are the thousand and one ways a skyscraper bleeds money. The first hit comes from the extra tons of steel and concrete necessary to keep it erect. As you increase a building's height, its bulk becomes a magnet for wind, which can send it toppling to the ground. The second hit comes from the revenue lost during additional construction time. The third hit is from the rentable floor area sacrificed to the extra structure. And finally, when the giant tower is drywalled and ready to use, it's inevitably too big — because no matter how hot the real estate boom, it's never easy to hawk millions of square feet at one time. Every developer knows that the Empire State Building sat empty throughout the Depression. Baker likes to describe his favorite clients, the guys who come to him with visions of clouds passing by their windows, as "not normal."

Like Donald Trump. In early 2001, Trump hired SOM to design the tallest building in the world — 2,000 feet, or about 160 stories. The kickoff meeting was set for the morning of September 11, 2001. Of course, that meeting never happened. The project stalled and was later reworked to become the merely giant 92-story Trump International that's rising today where the Sun-Times building used to be in Chicago.

But Baker never stopped thinking the 2,000-foot problem. For a proposed 90-story apartment building in Seoul called Tower Palace III, he and then SOM architect Adrian Smith worked up a Y-shaped plan that maximized the number of windows per apartment. Neighbors fought the developers down to a more modest 73 stories, but not before Baker saw something special in that Y: It was really strong. And shockingly light.

Each of the shape's three "noses" acted as a brace for the other two, so unless the wind was coming from every direction at once, there was always an unstressed segment to anchor it. But at supertall heights, the shape would twist — "like the dickens," Baker says. Though such motion poses little risk of causing what engineers call the overturning moment (which is exactly what it sounds like), the same can't be said for stomachs.

High in the air in a gently twisting building, the horizon seesaws. Nausea ensues. Baker worried that this would be a problem — perhaps the problem — for the future of supertalls. The capabilities of steel and concrete are one thing; the constitution of the inner ear is another. But he also saw a solution. If you connected each of the noses to a strong central core, the shape would not torque. Engineers — like astronomers and snowboarders — often get to name their discoveries. Baker called this the buttressed core. And of one thing he was certain: "If somebody really wanted to do the world's tallest building, this would be the way to go."

In spring 2003, a pair of developers invited Baker and two of SOM's managing partners to dinner at a restaurant overlooking the Manhattan skyline. The developers worked for a company in Dubai called Emaar, and they wanted to construct the tallest building in the world. Dubai was eager to make its mark, and because its ruler, Sheikh Mohammed bin Rashid al-Maktoum (known affectionately by locals as Sheikh Mo), supported the project, there would be no litigious neighbors or pesky air traffic controllers to muck things up. "There are some places in the world that are like, Let's do it, get it done,'" Baker says. "Dubai is one of those places." Emaar gave SOM two weeks to submit a proposal for a residential building, to be known as the Burj Dubai. The Dubai Tower.

Using the apartment building in Seoul as a starting point, Smith sketched a structure that stepped back as it rose, like a spiral staircase. He arranged the wings in a Y. "I knew from Bill that that shape would work well for a supertall," he says. Smith then rubbed out the sharp edges, replacing them with curved petals, like the flowers of the Arabian Desert. SOM got the job, and the buttressed core would have its day — the Burj would be the tallest building in the world.

The initial scheme was for a building of about 1,800 feet, 317 feet taller than the Petronas Towers. Yet the clients made a request: Overengineer the foundation, just in case we change our minds. Which the clients did. Repeatedly. On trip after trip to Dubai — even after a hole was dug and giant caissons were set 150 feet into the sand, even after the building began to rise, a floor every three days, into the desert haze — the SOM team kept getting the same request: Can you make it taller? They worked the problem in the wind tunnel, adding fins around the perimeter (like dimples on a golf ball) to create surface turbulence and reduce the lateral forces on the building. They worked the problem with concrete specialists, engineering a high-strength mix that could be pumped into the sky, like a giant drip-castle. But one thing needed no tweaking: the buttressed core. It seemed to permit limitless growth.

Most buildings are conceived with a set height, and the engineers work to that height — or whimper as the bankers slice it down. But Baker and his team found themselves testing the Burj to see how much taller it could go. "We didn't know," Baker says. "You get up as far as you think you can, and you see where you are, and you say, Oh. We still have some gas left in the tank.' But no one had ever been where we were."

The final height of the Burj will remain secret until its completion in 2009. SOM's managing partner George Efstathiou brags that it'll be as high as the Sears Tower and the Hancock Center stacked on top of each other (about 2,600 feet). Others say it could be taller — more than 3,000 feet. Baker thrills at the growing reality of it, but every once in a while he raps his knuckles on the table. "Quite frankly, I often urged the client to, you know — We can stop here, right?'" Baker says with a chuckle. "But they kept on pushing for taller and taller, and they were looking at me to see when I turned pale — so they'd know where to stop."

Smith remembers it differently. "Oh, we went beyond when Bill went pale, I can tell you that."

Contributing editor Andrew Blum (ab@andrewblum.net) wrote about green construction in issue 15.01.

FEATURE The Buttressed Core