Chaco Culture Historical Park
This pueblo was built between 900 and 1150 CE, an intricate and involved system of rooms fashioned by the Chaco people. It is very well preserved and to remain that way some of the area is closed off to visitors. It is said to have been one of the largest man-made structures in North America until New York started building skyscrapers. The pueblo is far off the beaten path and you'll have to drive several miles of county roads but this UNESCO site is well worth the trip.