Hoover Dam

Hoover Dam is a testimony to a country's ability to construct monolithic projects in the midst of adverse conditions. Built during the Depression; thousands of men and their families came to Black Canyon to tame the Colorado River. It took less than five years, in a harsh and barren land, to build the largest dam of its time. Now, years later, Hoover Dam still stands as a world-renowned structure. The Dam is a National Historic Landmark and has been rated by the American Society of Civil Engineers as one of America's Seven Modern Civil Engineering Wonders.

https://www.usbr.gov/lc/hooverdam/