This 7.8-miler chugs along an old railway bed, through five dynamite-blown tunnels to the Hoover Dam, a 726-foot-tall concrete plug in the Colorado River. From the visitor center, hike east on the Historic Railway Trail. In 1 mile, the trail dips into the first of five railroad tunnels blasted through the Aztec Sandstone Mountains in the 1930s. This rail line transported much of the supplies to build the second largest dam in the United States.
One of the best overlooks to Lake Mead is near tunnel 5. See the islands? Those are the tips of massive mesas. After the last tunnel, the trail descends 300 feet in 1.6 miles to the Hoover Dam. If time permits, check out the visitor center and tour the dam.