Another type of ruin that is not generally referred to as a ghost town, but that truly meet the definition, is an Anasazi ruin.

The Anasazi, or as is more politically correct, the Ancestral Puebloan Peoples, lived from approximately AD 1 to 1300, in the canyons and on the mesas in an area expanding out for about 250 miles in every direction from "Four Corners," where AZ, CO, NM, and UT come together.  For unknown reasons, they simply disappeared around 1300 AD.

From about 1100 to 1300 AD, they built complex villages located in canyon cliffs and on the mesas overlooking these canyons.  Because of their practice of building in cliffs, they are sometimes referred to as "cliff dwellers."  If you compare their 700 year old ruins to the ruins of "modern man" which are less than 100 years old, it may make you wonder who was more advanced.