A visit to Hoover Dam, located about 30 miles southeast of Las Vegas, is a must. An engineering wonder, the dam was built in the 1930′s to stop the flow of the Colorado River, which was wreaking havoc. The water was diverted to Lake Mead – now the largest man-made reservoir in the United States. Seventeen generators keep the dam going and you can choose from a couple of different guided tours to learn about the inner workings of the dam.