Hoover Dam

The Hoover Dam is as tall as a 60-story building, and when it was completed in 1935, it was the highest dam in the world. Each spillway can handle the same volume of water that flows over Niagara Falls. The concrete used could pave a road from San Francisco to New York City. But here’s the thing: you can’t build something that massive in the middle of the Nevada desert without infrastructure, so the government built an entire city first. Boulder City was the first fully planned new town of the 20th century- complete with paved streets, schools, a hospital, and housing for 5,000 workers. It cost $2 million and came with strict rules: no gambling, no drinking, no prostitution. A 69-year-old former newspaper editor named Sims Ely ran it like a fortified company town with total legal and moral authority. Workers lived in tent camps called Ragtown until the city was ready. The dam still holds back the largest man-made lake in the US, provides power and water to the Southwest, and welcomes a million visitors a year. Dam, that’s a lot.