Hoover dam has a tour but we only walked the top of the dam. There is also a hiking path that goes through several tunnels, but it was too hot for us to hike the day we went to the dam.
Historic Railroad Trail
We stopped at the Meade lake overlook before arriving at the parking ramp for the Hoover Dam. From the overlook we could see the History Railroad hiking trail that starts at the lake Meade park and ends at Hoover Dam. The trail is 3.7 miles long (one way).