City in the sky

Does Chicago owe its picturesque skyline to a birdcage?

By the late 1800s cities in the United States and around the world were running out of real estate. Some were hemmed in by waterways or other geographic obstructions and could not expand horizontally. Others had ample space but could not extend infrastructure fast enough to support an ever-growing physical space. Some just faced pressures to get as much rentable real estate as close to the central business district as possible.

To one degree or another, Chicago faced all three challenges.

By the 1870s Chicago was at a unique turning point. Population was surging as railroads brought more new residents to the city every day. A large-scale rebuilding project was getting underway as the city recovered from the 1871 fire which had devastated block after block of housing and the central business district. Since moving outward was not a viable solution, the city decided to move upward.

“Skyscrapers” got their start in New York City and quickly spread to other cities around the globe. They were limited at first in their construction by a series of factors which would have to be overcome if cities were going to rise more than about five stories off the ground.

The first challenge was a simple question of weight. The initial multi-story buildings consisted of bricks piled upon more bricks. The taller the building, the wider its base had to be in order to support the growing weight. As buildings got taller the walls of the lower floors got wider, squeezing out rentable space and such amenities as windows. Large scale construction was not going to be possible until designers found a way to build higher without completely squeezing out the space on the lower floors.

One of the architects wrestling with this problem was William LeBaron Jenney, a French-educated Civil War officer who came to Chicago as part of the growing building boom after the war. Coming home from work one evening Jenney was greeted by his wife who in the process of standing up from her chair placed the book she was reading on top of a nearby birdcage. Looking at the large book balanced atop the small birdcage, Jenney got an idea.

“If so frail a frame of wire would sustain so great a weight without yielding, would not a cage of iron or steel serve as a frame for a building?” wrote Jenney’s colleague Henry Ericsson of the moment of revelation.

Home Insurance Building, Chicago. 
Whether or not the story of Mrs. Jenney’s birdcage is just one of those Chicago legends like Mrs. O’Leary’s cow or Mr. Sianis’ billy goat, it nonetheless explains the principle of construction which would allow Chicago, in the space of just a few years, to rise higher and higher above the prairie. Jenney would incorporate this idea into the construction of the Home Insurance Building at LaSalle and Adams in 1883. Generally considered Chicago’s first skyscraper, the Home Insurance Building reached a breathtaking 138 feet high. In 1890 it would be extended up to 180 feet.

The most serious challenge the architects of the new city in the sky faced was the question of safety, and it was a question on everyone’s mind in the months and years after the fire which had laid waste to so much of Chicago. After the fire, amidst the rush to rebuild, several of the city’s business leaders such as George Pullman and Marshall Field had made it known that they would not be involved in the construction of any new, large buildings until their concerns about fire safety could be addressed. A number of insurance companies in the city also took a similar stand.

Unlike the earlier “fireproof” buildings that had proved to be anything but, these new buildings would not rely on wood or on largely decorative metal which had in some cases melted from the extreme heat of the fire. Architects solved this problem in Chicago by relying on stronger building materials like iron and eventually steel, and using masonry not as the primary means of supporting the building’s weight, but instead as a way to insulate the beams from fire. This combination of structural steel and reinforced concrete would become a mainstay of tall building construction around the world.

How to get people into the upper floors of these new buildings was yet another challenge to be addressed. An expression popular among landlords at the time was, “as the stairs marched upward, they met rental values coming down.”

No one wanted to walk up more than four or five flights of stairs, and building owners fretted about their ability to rent out office space or apartments on high floors which would involve such a climb each and every day.

Fortunately this was an era of rapid scientific exploration and discovery. Just as these decades saw Thomas Edison earn more than 1000 patents, other inventors of the age were themselves solving everyday problems that opened doors to creations unimaginable just a few years earlier. They were also making the new city in the sky possible. One of these, which had come along in New York just before the Civil War, was about to be improved upon in Chicago and made into a common feature of every tall building in the world today: the elevator.

Invented by Elisha Otis and dramatically demonstrated at New York’s 1853 Crystal Palace world’s fair, the elevator made it possible for people and goods to move quickly and easily between multiple floors of a building. In 1878 a Chicago inventor, C.W. Baldwin, worked with the Otis company to improve on Otis’ original design and developed the hydraulic elevator which was not only faster but smoother, thus making it possible for people to travel as high into the sky as architects could construct a building.

Similar technological innovations made it possible to make these upper floors comfortable enough for habitation, addressing such basic needs as heating and lighting, while new inventions like the telephone made instant communication between floors possible. Jenney’s birdcage design had the added benefit of allowing designers to use thinner support columns to carry the weight of the upper floors, making it possible for high floors to have wider windows, thus letting in more natural light and heat. Soon buildings around the country were reaching as high as 250 feet off the ground.

But while some architects were looking to the sky, John Wellborn Root was looking underground, trying to solve another problem which plagued construction in Chicago.

Conventional wisdom at the time suggested that such large buildings had to be anchored in bedrock, which in Chicago was as much as 150 below ground level. Digging that far was next to impossible without getting swamped by groundwater or having the walls cave in. Root’s solution was the floating raft: steel-reinforced concrete laid on top of hardpan clay, which would have enormous strength to support the building above. Root thus made it possible to construct skyscrapers on the reclaimed swampland that lay beneath most of downtown Chicago.

In 1885 the new 10-story Chicago Board of Trade building, designed by W.W. Boyington, reached 322 feet and eclipsed St. Michael’s Church to become the tallest building in Chicago, the first time an office building had held that title. A decade later it was replaced by the Masonic Temple Building designed and built by Daniel Burnham and Root. At 21 stories The Masonic Temple Building was so high that famed Illinois author Edgar Lee Masters would later write that from its top “one could see Council Bluffs, Iowa, 230 miles distant.”

Jenney’s Home Insurance Building set off a rush of tall building construction in the area around downtown Chicago, put together by some of the nation’s most famous names in architecture. Burnham and Root’s Montauk Building rose in 1882, and their Rookery Building followed in 1888 with a redesign by a young architect named Frank Lloyd Wright in 1902. In 1889 Louis Sullivan and Dankmar Adler collaborated on the massive, multi-use Auditorium, the cornerstone for which was laid by President Grover Cleveland with the dedication a year later keynoted by President Benjamin Harrison.

Chicago’s vertical growth was attributable as much to the visionary architects as it was to the city’s aspirational business leaders. Sullivan would write that, “The modern office building is the joint project of the speculator, the engineer, the builder.”

Some of these buildings were demolished for new construction years later, some still stand today. Eventually these innovators developed a whole new style of building construction which came to be known as the Chicago School. These architectural geniuses combined with a workforce of thousands to create a whole new skyline for Chicago just in time for the 1893 World’s Columbian Exposition world’s fair. For some visitors the skyline itself was just as much of an attraction as the fair.

Their work in pushing downtown Chicago upward to become a city in the sky revolutionized city planning and construction. The skyline reached its record height in 1974 when Chicago opened the tallest building in the world.