1913

Woolworth Building

Gunvald Aus (1851–1950), Cass Gilbert (1859–1934), Korte Berle (Dates Unavailable)

An architect or engineer working in the 1700s was using wood, stone, and brick for construction. Exterior walls and interior columns carried all the load. With stone, making a multi-story building taller means that the walls, especially at the bottom, have to be thick. Windows weaken the structure, so they have to be small.

In the 1800s, cast iron appeared. Columns and walls could be thinner and windows could be bigger, but building height was still severely limited. Seven or eight stories was the maximum height.

All that changed with the introduction of cheap steel created by the Bessemer Process. Because of steel’s strength, frameworks of steel I beams could rise to amazing heights and less of the building’s load had to be carried by exterior walls. The exterior walls of modern skyscrapers are called curtain walls to reflect how much their role has changed—the exterior walls can hang off the steel structure rather than vice versa. If engineers want the exterior of a building to be entirely glass, that is possible with modern structures.

Other technologies helped to enable the rise of skyscrapers. Skyscrapers would be impossible without elevators—no one would be willing to walk 50 flights of stairs. Auxiliary pumps and storage tanks make it possible to have water pressure in tall buildings. All of these elements came together in the late 1800s.

New York’s Flatiron Building had 21 floors and used all of these techniques in 1903. But was it a “skyscraper”? Engineers upped the ante very quickly. Just 10 years later the Woolworth Building with 60 floors became the world’s tallest building for the next 17 years. Its height and appearance make it undeniably a skyscraper in the modern sense. The Woolworth Building, designed by architect Cass Gilbert and constructed with the assistance of structural engineers Gunvald Aus and his partner Korte Berle, was an amazing engineering achievement at the time, with 34 high-speed elevators, 5,000 windows, and nearly a million square feet (93,000 square meters) of floor space.

Skyscrapers demonstrate a consistent engineering theme—when new technologies and materials become available, engineers can create new things.

SEE ALSO Basilica of Saint Denis (1144), Bessemer Process (1855), Statue of Liberty (1886), Empire State Building (1931), Burj Khalifa (2010).

Woolworth Building under construction, 1912.