The construction industry has been around for a long time, and makes for some really strange, fun, and interesting facts. From massive skyscrapers that pierce the clouds to incredible technology discoveries and inventions, the industry wows every single day. Here are 10 facts about the construction industry that you probably don’t know—but definitely should.

1. Concrete is the most used material.

In terms of volume, concrete gets used the most in the world— and actually dates back to Ancient Egypt! Unfortunately, it has also been known as one of the most environmentally unfriendly. However, that’s been changing thanks to great innovations that have reduced their gas emissions and permeable rendition. There’s also now pollution-absorbing cement.

2. The famous “Lunch Atop a Skyscraper” picture is real.

There was some debate about this picture from 1932, showing eleven men eating lunch on a beam from the GE Building. One of the big reasons for the controversy is that the photographer wasn’t identified until 2003. The picture—which was originally used for a commercial poster—became a famous icon and had been recreated with well-known actors in the late 20th century. It turns out that the original picture incredibly had no alterations or darkroom tricks made to it.

3. Women earn almost as much as men!

Although there’s only about 9% of workers in the US construction industry that are women, they do earn closer to what men earn, on average.

4. The average age of a construction worker today is 42 years old.

This is one year older than the average age of a worker in the general labor force. The ongoing shortage of construction workers and an aging workforce have contributed to the increase in the median age of construction workers.

5. Count the nails.

When building an average-size house—about 1,200 square-feet—there are about 12,000 nails used.

6. The world’s smallest skyscraper was a con.

Back in 1919, a contractor named JD McMahon raised $200,000 from investors to build a skyscraper in Wichita Falls, Texas. But apparently, he never verbally stated the planned height of the building. Although the blueprints showed 480” (inches), his investors apparently never caught on, and thought they were getting a tall 480 foot—not 40 foot—skyscraper.

7. Drone use has increased. 

As technology has improved over time, construction methods have improved as well. For instance, drone use on construction sites has grown over 239 percent in the past year, the most of any industry. Why? The aerial maneuverability of drones and the ability to record videos and take photos have streamlined and improved the construction project.

8. Most fatalities occur because of a fall.

It’s no surprise that training for safety is crucial. As the demand for craftsmen has gone up, so has the injury rate. Falls are by far the biggest risk, and result in death four more times more than other fatal incidents.

9. World War II encouraged women to enter the construction industry.

During World War II, thousands of women worked construction jobs—between 1940 and 1945, the female labor force grew by 50 percent. After the war ended, up to 85 percent of women wanted to keep their jobs, effectively paving the way for women in the construction labor force.

10. Younger generations are less interested in the construction industry.

According to U.S. Census data, the number of workers aged 24 years or younger entering the construction industry decreased by 30% between 2005 and 2016. They have misconceptions—like that the construction industry is somehow unstable or you can’t earn a lot of money compared to college-educated careers. With cities across the country hiring for construction jobs, there’s never been a better time to start a new career in construction.