The Empire State Building is a 1,454 feet tall 102-story skyscraper sitting between 33rd and 34th streets on Fifth Avenue in Midtown Manhattan.

For almost four decades, from its completion in 1931 until the World Trade Center’s North Tower was completed in 1970, it was the tallest building in the world. At one point, the American Society of Civil Engineers named it one of the Seven Wonders of the Modern World.

On January 22, 1930, excavation of the site began, and by March 17, construction began in earnest. It took 3,400 workers, most of who were European immigrants, and hundreds of Mohawk ironworkers to finish the project.

Construction required a massive amount of material. In the end, it took 200,000 cubic feet of limestone, 10 million bricks, and 60,000 tons of steel.

If you’ve seen the photos, you’ll also know that it’s well-known for its lack of safety regulations. Yet, despite that, only five workers died during the construction.

The Empire State Building’s construction was also part of a larger competition for the world’s tallest building in New York City. Eventually, it would beat out 40 Wall Street and the Chrysler building.

On April 11, 1931, barely a year after it began, work on the Empire State Building was finished. Below are some fantastic photos of the process.