How They Built the World’s Most Famous Landmarks

Taming the wild Colorado River was one of the greatest American engineering projects of the 20th century. Before its completion in 1936, the Boulder Dam, later renamed the Hoover Dam, was a massive construction site in the middle of the desert. This aerial view shows the colossal structure just before it began to hold back the water that would form Lake Mead, bringing power and water to the developing Southwest.