On previous trips to the area, the Grand Canyon has been one of my favorite day trips of all time but the Hoover Dam was wondrous as well. The history behind this Dam and how it changed the landscape of so many states is fascinating. Free to get into the main area but you have to pay $15 to explore the lower area, $10 to go to the museum/observation deck and $30 for a guided tour below. The museum is great for history buffs and scientists. The drive is a quick 45 minutes from the Las Vegas strip.