Rising more than 700 feet above the raging waters of the Colorado River, Hoover Dam was called one of the greatest engineering works in history. 5,000 working men and their families came to live ...
6.This is what a typical day of air travel over Europe looks like: 7.This is what a "9 out of 10 difficulty level" puzzle looks like: 8.This is what a Hoover Dam spillway tunnel looks like.