The Mystery of Chaco Canyon

Chaco Canyon, located in northwest New Mexico, is perhaps the only site in the world constructed in an elaborate pattern that mirrors the yearly cycle of the sun and the 19-year cycle of the moon. How did an ancient civilization, with no known written language, arrange its buildings into a virtual celestial calendar, spanning an area roughly the size of Ireland? Chaco Canyon, located in northwest New Mexico, is perhaps the only site in the world constructed in an elaborate pattern that mirrors the yearly cycle of the sun and the 19-year cycle of the moon. How did an ancient civilization, with no known written language, arrange its buildings into a virtual celestial calendar, spanning an area roughly the size of Ireland?