Environment: The Tallest Skyscraper

In 1885, Chicago became the proud possessor of the world's first true skyscraper, the nine-story, steel-framed Home Insurance Co. building. Within a decade, however, New York City captured the tallest skyscraper lead—and held it. The champion until last month was Manhattan's 1,350-ft.-high, twin-towered World Trade Center, which tops the Empire State Building by 100 ft. But now, after a lapse of about 80 years, Chicago again boasts the tallest tower: the $150 million Sears, Roebuck & Co. building, which soars 1,450 ft. above the city.

Sears executives offer a simple explanation for their record-breaking new building. Says the company's recently retired chairman, Gordon Metcalf: "Being the largest retailer in the world, we thought we should have the largest headquarters in the world." But the genesis of the Sears Tower is more complicated than that. When the company decided to leave its sprawling old headquarters on Chicago's deteriorating West Side, height was the furthest thing from the executives' minds. They had bought a two-block plot on the western edge of Chicago's Loop and approached the problem of building the headquarters in exactly the same way as they planned any of Sears' stores throughout the world—from the inside out.

The company began by studying its space needs, down to the number of desks for personnel. Then it projected its office requirements to the year 2003. Next, Sears hired the New York design firm of Environetics to recheck the projections, draw floor plans, and figure out where every department should be located in relation to every other department. The result was a drawing that Environetics President Larry Lerner calls "a building profile"—a jagged shape that looks like a child's random construction with wooden blocks of varying sizes. When this interior scheme was shown to the building's architect, Bruce Graham of Skidmore, Owings & Merrill, he gasped: "How do you expect me to design around that!"

But S.O.M. soon had an ingenious solution. Graham's engineer-partner, Fazlur Khan, illustrates the concept by grasping a bundle of nine upright cigarettes. Each represents, in effect, a separate, square building, 75 ft. by 75 ft.; joined together, the nine square "tubes" form the basic structure of the Sears Tower. By combining all nine tubes —each of which is inherently a strong, rigid shape—the building needs less structural steel than a conventional tower. The saving: about $10 million in steel costs.

More important, this arrangement is tailor-made to Sears' office requirements. The company wanted huge rooms to house its current departments and employees, plus floors that could be rented until the fast-growing company expanded into them. Most renters, however, do not need vast interior spaces; they want windowed offices around a compact central area. To get both kinds of floor layout, the architects terminated two of the tubes at the 50th floor level, two more at the 66th floor, and another two at the 89th floor —thus creating much smaller, and more rentable spaces on the higher stories. Sears itself will occupy the lower 50 floors of the tower—where the nine square tubes are clustered to form about 60% of the building's volume.