Who built the Empire State Building, and how long did it take to build it?

It took just 410 days to build the Empire State Building. The contractors who pulled off the feat won the massive bid with a bizarre boast: they owned absolutely zero construction equipment.

The firm was Starrett Brothers and Eken, the premier skyscraper builders of the era. They were hired by former General Motors executive John J. Raskob and former New York governor Al Smith, who conceived the project to outdo the neighboring Chrysler Building. During the bidding process, Paul Starrett won the developers over by arguing that relying on old machinery would only cause delays. Instead, his firm promised to buy entirely new, custom equipment specifically for the Empire State Building and sell it as scrap afterward.

Architect William F. Lamb of Shreve, Lamb & Harmon drafted the building’s design in just two weeks. His plans were driven by strict zoning laws and the need to maximize natural light, resulting in the iconic tiered shape.

Construction officially began on March 17, 1930. Starrett Brothers approached the site like a military logistics operation. Because Manhattan’s streets were too congested to stockpile steel and stone, materials were delivered precisely when needed. The contractors installed a temporary railway system inside the building, complete with carts on tracks, to quickly distribute materials across the massive floor plates.

A construction worker balances on the steel framework of the Empire State Building in 1930, part of a labor force that erected the structure at a rate of 4.5 stories per week. Source: Wikimedia Commons.

At its peak, a workforce of over 3,400 men—including skilled Mohawk ironworkers—drove the steel frame skyward at a rate of 4.5 stories per week. Instead of waiting for the frame to be completed before starting the exterior, the masonry and brickwork chased the steel up the tower just a few floors behind.

The building officially opened on May 1, 1931, just one year and 45 days after the first steel columns were set. Not only was it completed months ahead of its already aggressive schedule, but it also came in well under its $50 million budget, cementing Starrett Brothers and Eken as the master builders of the 20th century.

Why did Al-Qaeda choose the World Trade Center rather than the Empire State Building? Isn't the Empire State Building more of an American symbol than the Twin Towers?

 Bin Laden had an engineering background.

The choice was symbolic, it's true, but he knew that the Empire State Building was built far more solidly than the World Trade Center. Both buildings naturally exceeded the required load-bearing capacity, but due to limitations of some of the construction materials used, this is how the Empire State Building was built.

This is the Empire State Building under construction. It's all steel. You can see the beams extending from the top to support the future floors. There's a steel column roughly every 2.5 meters throughout the structure. It's also covered in masonry.

In comparison, here is the construction of the World Trade Center.

The core of the building features beams every 3.5 meters, but most of the building's structural strength is located on the exterior, which is constructed as if it were a solid steel box. From the architects' perspective, this was an advantage, as it allowed for significantly more open space within the building.

There's no masonry on the exterior, just steel and glass. The steel is very strong, but there are windows sandwiched between the steel sections.

In fact, the Empire State Building had already survived a collision with an airplane.

Yes, there was a fire, but because the interior walls were lined with masonry and the floors were concrete, the fire never reached the two floors directly impacted by the crash. The building was repaired to like-new condition.

Thus, even a heavier plane would not have brought down the Empire State Building - it simply had too many redundant supports.

Afterwards, Bin Laden did not expect the towers to collapse (it was lucky for him), but he expected, because of their construction, that the damage would be much greater and that the fire would spread more, which happened in both cases.