A true historic gem along Route 66, Hoover Dam is a must-visit spot, especially for engineering enthusiasts. When it was completed in 1930, it stood as the tallest dam in the world. Not only does it provide water for recreational purposes in Lake Mead, but it also controls flooding of the Colorado River and irrigates vast farmlands spanning over 1,500,000 acres. There is a fee if you want to park near the bridge, along with a government checkpoint to enter. If you want to witness the dam for free and aren’t afraid of heights, you can walk along the Mike O’Callagham-Pat Tilman Memorial Bridge.