Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Arizona and Nevada. When completed in 1936, it was both the world's largest hydroelectric power generating station and the world's largest concrete structure.

Fun facts: Type: Arch Gravity; Height: 726.4ft; Crest Length: 1244ft; Crest Width:45ft; Base Width: 660ft