Hoover Dam, one of Las Vegas" most famous attractions, lies only 30 miles from the City. Nestled between the walls of imposing Black Canyon, the Dam"s massive retaining wall stops the Colorado River in it"s tracks, thereby creating the U.S."s largest reservoir and generating in excess of 4 billion kilowatts-hours of electricity. You can tour the structure by foot. However, if you really want to experience the magnificence of the Dam, you should consider booking a helicopter trip.