Chicago Skyline. In the late 19th century, Chicago’s downtown was an ideal location for architects of ambition; the Great Chicago Fire of 1871 had literally gutted the downtown area, creating a relentless drive to re-build and ample space in which to do it. Chicago’s engineers solved the problem of the load-bearing wall, liberating structures from the limits of what a masonry foundation could support. Built in 1885, William LeBaron Janney’s 10-story Home Insurance Building was the first to use a steel-frame skeleton to support its walls — at one-third of the weight of a structure using conventional means. Real estate prices and building heights soared in the years that followed, but the boom years of the 1920s financial bubble saw an unprecedented wave of skyscrapers that shattered previous records for size, including the still-extant Mather Tower, Tribune Tower, and later the Chicago Board of Trade.
The second wave, oddly enough, occurred during the 1960s and 70s, when urban centers across America were experiencing white flight and severe population decline. The answer of Chicago’s first Mayor Daley was simple: build, and then build some more. As a result, while the residential population spread across a wide range of suburbs, commercial activity remained fixed at the center of the city. It was during this time when Chicago gained its most famous modern skyscrapers, including the three of the tallest: the Sears Tower, the Aon Center, and the John Hancock Center. (It was also during this time — as occurred during the first wave — when a giant swathe of early skyscrapers were recklessly demolished.)
The third wave of supertall construction is underway right now. Driven by downtown Chicago’s residential real estate boom (the hottest in the country prior to the late 2000s financial crisis), existing buildings are converting office space to condominiums and hotels, and builders are racing to erect what will be some of the world’s tallest buildings, which may radically re-shape the city’s skyline. The latest result of the building spree is, of course, the Trump Tower, now the fourth tallest building in the U.S., and the 16th tallest in the world. Eventually, construction ground to a halt as virtually all sources of credit dried up, leaving a few of the most intriguing projects in jeopardy, including the now cancelled Chicago Spire.