The Hoover Dam is an amazing site to see, particularly from the top of the dam looking back at Lake Mead, and from the Pat Tillman Memorial Bridge (US-93) that runs above it. We planned to do the guided dam tour offered by the NPS, but it was shut down the day we went (Labor Day) because of a mechanical issue. But they still were doing the guided power plant tour, so we did that one instead. The tour was a ride down the original elevator in the dam, walk through a tunnel to the turbine room, then stand on a platform and talk about the turbines. That was it. I hope the full dam tour is better, because if I had it to do all over again, I would have saved my money and just walked across the dam and the bridge (which we did anyway), and both of those activities are free. But regardless, it's definitely something worth seeing because it truly is a marvel.