The Hoover Dam is amazing. Every time, I visit I'm amazed at this engineering marvel. We did the Guided Tour that includes the tour of the Power Plant. They have a quick 5-10 min movie about the building of the Dam before they take you in the elevator down into the Pipes & Power Plant on the Nevada side of the Dam. You can feel the turbines under your feet. Then, you can go up to the Observation Deck over looking the Hoover Dam and giving you a nice view of the New Bypass Bridge. We spent an hour walking around the outside of the Dam, changing time zones between AZ & NV and enjoying the views and the construction of the Dam itself. The visitor center & gift shop are very nice. You can either park at the Visitors Center or drive across the Dam and park on the AZ side of the Dam. You don't need to pay to see the Dam in it's glory. A must see when you visit Las Vegas.