In 1872, a 28-year-old apprentice draftsman named Daniel Burnham opened an architecture firm with his good friend, John Root. Burnham and Root would soon become one of the finest architectural firms in Chicago.
Among the firm’s best work is the Monadnock Building, in Chicago’s Loop, at the corner of Dearborn and Jackson. If you have time, or when you tour Chicago, I hope that you will see this building. There’s a very good coffee shop there, and a hat shop, and a great, old shoe-repair business. If you go to visit, pay particular attention to the walls. They are 6 feet thick, almost 2 meters, at the base. They had to be that wide to support the weight of the 16-story-high building.
For thousands of years, buildings had to have thick walls because the walls carried the weight of the entire structure. The higher the building, the thicker the walls had to be. The Monadnock Building represented an amazing architectural achievement: it was the tallest load-bearing building ever built, and it was the tallest office building in the world. John Root called this building his “Jumbo.” It was his last project because he died suddenly of pneumonia while it was under construction.
But the Monadnock Building was a great achievement that also represented the limits of an age-old concept. It made sense that the walls had to be heavy and strong in order to hold the weight of the building. But with load-bearing walls, a building can only go so high. As the ambitions of city planners and residents rose, so did the desires of architects and their clients to build even higher. But how could you build a really, really tall building without building really, really thick walls?
A man named William Le Baron Jenney came up with the answer. Jenney is widely recognized as the father of the American skyscraper, and according to Chicago lore, he had a breakthrough idea when he observed his wife placing a very heavy book on top of a tall metal birdcage. The cage not only supported the weight of the book, Jenney could see that it could have easily supported a whole stack of books. A stack of books piled high and balancing on a birdcage—what an image.