Hoover Dam, on the border between Arizona and Nevada, USA

Happy birthday, Hoover Dam! President Franklin Roosevelt dedicated this engineering marvel 80 years ago today, and it still stands as a testament to the ingenuity, perseverance, and sheer hard work of the thousands who labored in harsh conditions for over five years to tame the flow of the mighty Colorado River and turn it into hydroelectric power.

When it was completed, Hoover Dam was the largest dam in the world. It required nearly 88 million cubic feet of concrete, which made it the first single structure to use more masonry than the Great Pyramid of Giza. All that concrete was poured into individual, rectangular-shaped sections that were then cured using over 582 miles of cooling pipes. If the concrete had been poured in a single, continuous pour—and left to cool naturally—it would still be settling today.