Dating back to as early as 1150 ., the ruins of Mesa Verde are one of the oldest in America. They are set in the Mesa Verde National Park in Colorado, USA and are all that is left of the ancient Pueblo people, also known as the Anasazi. Around 600 houses dug in the cliffs of Colorado can be found through the park, most of them very small, but some are absolutely huge, able to house more than 250 people. The Anasazi came to these places around 550 A.D., but only started digging their dwellings into the canyon cliffs around 1150.