12,000-year-old unexplained structure
For a more thorough analysis related to the geological existence for sites such as these, visit the trailer of an up and coming documentary: http://www.youtube.com/watch?v=uIdSAR0I-BQ
Amazing find (History Chanel docum.) in what is now Turkey, 12,000 year-old circular city. Twice as old as any city in Mesopotamia. The Germans are excavating it.
No stone-cutting tools used."