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Podcast Transcript
If you were to pick a single visible icon to represent the 20th century, it would probably be the skyscraper.
Skyscrapers didn’t really even exist before the 20th century, but by the end of the century, they became ubiquitous in major cities around the world.
The skyscraper didn’t just appear out of nowhere. They wouldn’t have been possible if it wasn’t for multiple technical innovations. Continued innovations have allowed skyscrapers to get taller and taller.
Learn more about skyscrapers, how they were developed and how they kept growing on this episode of Everything Everywhere Daily.
Prior to the development of skyscrapers, all buildings were mostly made out of wood, stone, or brick. These materials were fine for the most part, and you could indeed create incredible structures with just those three materials. The Colosseum in Rome, the Great Wall of China, the Taj Mahal, and the Pyramids, as well as all the castles, and cathedrals were all made of wood, stone, or brick.
In the 19th century, cities grew larger, which put pressure on finding space for everyone. There were only two directions a city could grow: out or up.
Most cities did expand their borders outward depending on where they were. A city like New York (and New York City was the island of Manhattan for most of the 19th century before the Burrough merger) had nowhere to go.
Even if a city could sprawl outward, there was still demand for space in the city center. This required the construction of taller buildings.
However, there was a problem. There was a limit to how tall you could reasonably build a brick building. In ancient Rome, apartment buildings known as insulae were recorded as being nine stories tall, but eventually, limits were placed on how tall they could go because they were simply too dangerous.
Constructing very tall buildings out of brick, which had become the dominant building material in the 19th century, presented two major problems.
The first problem was a human problem that was something the Romans realized: The taller the building, the harder it was to reach the top floor. In modern buildings, the top floor is often called the penthouse, which is the most valuable part of the building.
In Rome, the top floor was the cheapest part of the building because it required so much work to climb up and down every day.
No matter how cheap it was, there was a limit to how much anyone would walk vertically for any building.
The second problem was structural.
Brick and mortar are heavy materials. As a building gets taller, the weight of the bricks at the top must be supported by those below. This increasing weight exerts a significant amount of stress on the lower levels.
Beyond a certain height, the bricks at the bottom cannot support the weight above.
Brick has limited compressive strength. Compressive strength is the capacity of a material to withstand loads that attempt to compress it. In tall buildings, the stress on the lower bricks can exceed their compressive strength, leading to structural failure.
The only way around that is to make the base of the buildings extremely wide. However, there is a limit to how wide a building’s base can be before it loses functionality. If you can’t use the bottom floors, adding more floors to the building defeats the purpose.
Stone had a higher compressive strength, but it was more difficult and expensive to work with.
For all practical purposes, brick buildings could only be built to about a six-story height. Taller brick buildings were built, but they were challenging to build, live in, and work in.
The first big innovation which paved the way for the skyscraper was the safety elevator. Elisha Otis created his elevator in 1857 and I have previously dedicated an episode to the subject. Otis’s elevator was a safe way to transport people vertically in buildings.
There were lifting systems previously, but they had a spotty safety record, and people were afraid to ride in them. With an elevator, people could now easily reach the upper floors of buildings.
The first commercial building with an Otis Elevator was the Equitable Life Building in Manhattan, which opened in 1870.
This, however, didn’t solve the structural problem of bricks.
The answer to the brick problem lay in iron and steel. It was realized that you could create a metal skeleton for a building that would carry the building’s load. It didn’t have to be carried by the walls of the building as it did with brick.
The first building of this type ever built was the Oriel Chambers Building in Liverpool, England. Built in 1864, it had a cast iron frame. Because the Frame of the building carried the load, the walls had very large windows. Large windows on a building weren’t previously possible because you couldn’t take up that much wall space with windows because the walls had to bear the load of the building.
These non-load-bearing walls are known as curtain walls.
The Oriel Chambers Building was not a skyscraper as it was only five stories tall, but it did have many of the elements that would make skyscrapers possible.
The first building considered to be a true skyscraper was the Home Insurance Building in Chicago, Illinois.
Built in 1885, it stood ten stories tall, and two more stories were added in 1891. Designed by architect William Le Baron Jenney, it had an iron frame.
The Home Insurance Building was also the first building in what would become the Chicago School of Architecture. The Chicago School adopted modern building techniques to make taller buildings.
A host of skyscrapers were built in the following years.
Chicago’s 13-story Tacoma Building was built in 1889.
That same year, the 10-story Rand McNally Building, the first building with a full steel frame, was also built in Chicago.
Here, I should note the innovation that made this possible: the Bessemer Process.
Steel is much stronger than cast iron. Although steel has been known for centuries, it was difficult to create in mass. The Bessemer Process, patented in 1856, allowed for the mass production of steel, which allowed the creation of steel beams to make skyscrapers.
In 1892, the Masonic Temple Building was constructed, which had 21 stories and was the tallest building in Chicago.
The transition to steel structures wasn’t abrupt. Brick buildings were still being built. Most notable was the Monadnock Building in Chicago. It was a 16-story all-brick building, the tallest load-bearing brick building ever built.
The Monadnock Building is still standing today. One look at it, and you can see why brick buildings couldn’t get much taller. The base is very thick, and it tapers as the building goes up.
The Monadnock Building also showed another problem with brick as opposed to steel: wind. As buildings get taller, the forces of wind become a greater problem.
The issue of wind is so important that some structural engineers define a skyscraper as any building where wind is a more significant structural load factor than weight.
In a brick building, the forces are almost all pointing down into the bricks. In a steel structure, however, lateral forces from wind can be directed into the frame of the building.
While Chicago was the home of some of the first skyscrapers, the city eventually capped the maximum height of buildings, which allowed New York City to take the skyscraper mantle.
New York’s 22-story Flatiron Building, completed in 1902, has a unique triangular design made possible by its steel frame.
Heights rose quickly. The Woolworth Building, constructed in 1913, had 55 stories and stood 792 feet, or 241 meters, tall, making it the tallest building in the world at the time.
It had 34 electrical elevators and more than 100 years after its construction, it remains one of the 100 tallest buildings in the United States.
The 1920s and 30s saw a competition amongst New York skyscrapers, culminating in the Empire State Building. The 102-story building had a peak height of 1,454 feet or 443.2 meters. It was the tallest building in the world for almost 40 years.
Until the 1930s, skyscrapers were mostly an American phenomenon. However, in the 30s and 40s, there was an explosion in skyscraper buildings around the world.
The largest collection of skyscrapers was in the Soviet Union. Known as the Seven Sisters, these Stalinist-era buildings were the largest in Europe at the time. The tallest of the buildings was the Main building of Moscow State University. It stood 239 meters or 784 feet tall and was Europe’s tallest building until 1990.
All of these skyscrapers didn’t really look like the skyscrapers we know today. The modern-looking glass skyscraper was developed by the architect Ludwig Mies van der Rohe in the 1950s.
Van der Rohe noticed that all the skyscrapers tried to look like they weren’t. Almost all of them had some sort of stone facade, like the Empire State Building, which was clad in limestone.
Van der Rohe began designing buildings that were entirely covered in glass. One of the first glass facade buildings was the Seagram Building in New York City, completed in 1958.
Van der Rohe wasn’t the first architect to create such buildings. The United Nations building was completed in 1952. However, he popularized such buildings, which became known as the International Style.
Skyscrapers with an entirely glass facade wasn’t just a design choice. Glass was lighter than limestone, which removed stress from the building. It also brought in more light and made the interior spaces feel more roomy.
In the early 1960s, the Bangladeshi-American structural engineer Fazlur Rahman Khan developed a new system called “tubular design.”
Rather than a building with a metal skeleton holding everything together, you could achieve the same thing by having a rigid metal tube outside the building. By tube, it doesn’t have to be circular; the metal on the outside of the building could create a hollow tube to support the building.
The first such building was the Plaza on DeWitt, which was finished in 1966 in Chicago, Illinois.
The design style quickly caught on as it allowed buildings to be taller than before. This technique was used in the John Hancock Center and Sears Tower in Chicago, the World Trade Center towers in New York, and the Petronas Towers in Kuala Lumpur, Malaysia.
Eventually, as skyscrapers reached well over 100 stories, steel, too, ran into problems, just like brick did a century earlier.
When the Emirate of Dubai commissioned the Burj Khalifa, a tower that would dwarf any human structure in history in terms of height, the architectural firm of Skidmore, Owings & Merrill decided to take an entirely different approach.
Instead of a steel frame or tube, they used reinforced concrete. Concrete has incredible compressive strength so that it can withstand the forces pushing down from the tower’s weight. The Burj Khalifa wasn’t the first concrete structure, or even the first concrete structure tube design.
It was the first to use a new design, invented by the architects, known as the Buttressed core. The layout of the Burj Khalifa looks like the letter Y, with three different buildings connected to provide lateral support for the entire building when it encounters high winds.
Instead of hauling up steel girders, they had to overcome the engineering challenge of pumping up cement to such a high height.
Reinforced concrete with a Buttressed core, like the Burj Khalifa, is being looked at for many of the next generation of super-skyscrapers.
The Jeddah Tower, which is currently under construction in Saudi Arabia and will be the first building in history to reach a height of one kilometer, will be using reinforced concrete and a Y-shaped buttressed core.
The desire for ever-taller skyscrapers will constantly push the need for new construction techniques and materials to make these dreams possible.
In the short span of a little more than a century, we’ve gone from bricks to steel beams to reinforced concrete, which has resulted in skyscrapers of heights that previous generations couldn’t have even imagined.
