The massive buildings of the ancestral Pueblo peoples still testify to the organizational and engineering abilities not seen anywhere else in the American Southwest. For a deeper contact with the canyon that was central to thousands of people between 850 and 1250 A.D., come and explore Chaco through guided tours, hiking & biking trails, evening campfire talks, and night sky programs. The majority of the park and cultural sites are self-guided year-round. Six major sites are located along the 9-mile long Canyon Loop Drive. These sites include Una Vida, Hungo Pavi, Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo, and Casa Rinconada. You may purchase self-guided trail guides at the Visitor Center bookstore. Ranger-led walks of Pueblo Bonito are offered year-round. Four backcountry hiking trails lead visitors to remote Chacoan sites, passing ancient roads, petroglyphs, stairways, and spectacular overlooks of the valley. The trails are open from 7am until sunset. For your safety and protection permits are required, free at the Visitor Center and at the trailheads. There is no overnight backcountry camping; camping is only allowed in Gallo Campground. In 1987 Chaco Culture was inscribed on the UNESCO World Heritage List as an outstanding example of world cultural patrimony. The World Heritage designation is an honor meant to recognize the uniqueness of the civilization centered at Chaco Canyon from 850AD to 1250AD.