Most Viewed Keyword Petroglyph

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?

Did intelligent beings from outer space visit Earth thousands of years ago? From the age of the dinosaurs to ancient Egypt, from early cave drawings to continued mass sightings in the US, each episode gives historic depth to the questions, speculations, provocative controversies, first-hand accounts and grounded theories surrounding this age old debate.