The Hoover Dam was one of the great engineering feats of the Great Depression of the 1930s in the United States. And impressive it is.
At its base, the massive concrete wall is 660 feet thick, so thick that the concrete is still curing. That means that unlike most constructions that are fighting against aging from when they're built, the hoover dam is actually getting stronger. At the bottom of the massive wall are two hydroelectric power plants, one on the Arizona side and the other on the Nevada side, each housing eight or nine enormous turbines.
The tour guides are careful to point out that the purpose of the dam is not to supply power to Las Vegas and that in fact none of the electricity generated at the Hoover Dam finds its way to that poster-child for consuming electricity with wanton abandon. And aside from generating electricity, the dam performs a vital role in controlling and distributing water supplies downriver.