Sandstone ruins,


Chaco Culture National Historical Park is a United States National Historical Park hosting the densest and most exceptional concentration ofpueblos in the American Southwest. The park is located in northwestern New Mexico, between Albuquerque and Farmington, in a remote canyon cut by the Chaco Wash. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian cultural and historical areas.[2]
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples.[a] Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century.[2][4] Evidence of archaeoastronomy at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles,[5] requiring generations of astronomical observations and centuries of skillfully coordinated construction.[6] Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.