Its geologic layers tell a tale that goes back more than 1.8 billion years, including the period 6 million years ago when the Colorado River first raised its carving knives.
The landscape is a study in maximalism, with a frozen lava flow, waterfalls and a white-water river rushing through its veins.
(Albuquerque lies 180 miles to the southeast.) Aztec Ruins is in Aztec, New Mexico, 20 minutes from Farmington.
Best time to visit: Spring or fall, when the weather is halfway between scorching and freezing.
The Grand Canyon Railway offers daily train service between Williams, Arizona, and the park.
Best time to visit: Spring or fall, when the heat won't melt your inner thermostat and the facilities on both rims are open.Insider tip: The Chaco Culture park, which was certified as an International Dark Sky Park in 2013, holds telescope-peering events from April through October.At Aztec Ruins, go semi-deep inside the only reconstructed kiva in the Southwest.How to reach it: The park has three entrances in three cities: Homestead, Miami and Everglades City.Visitors can access all entry points by car and the Flamingo and Gulf Coast districts by boat.For more than 40 years, the United Nations Educational, Scientific and Cultural Organization and its nearly 200 member states have been preserving, protecting and promoting the most valuable heritage places in the world.At last count, the organization has crowned 1,073 sites in more than 170 countries. 1050 to 1200 still exist, including the 100-foot-tall Monks Mound, the largest earthwork in North America and the only mound visitors can climb.The hot effusions are continually retouching the tropical landscape, a haven for native birds and endemic species such as a meat-eating caterpillar, a lava-loving cricket and the world's rarest goose.How to reach it: The park is about a 45-minute drive from Hilo, on the island of Hawaii.Approximately 400,000 Brazilian free-tailed bats vacation in Carlsbad Cavern from late May through late October.How to reach it: El Paso is about 2 1/2 hours away by car.