Unexplained 12,000 Year old Underground City

According to Schmidt, it seems that agriculture began here, in the province immediately surrounding Gobekli, sometime around 8,000BC.

This indeed was one of the very first places in the world where people farmed. We know roughly when and where farming began, because of the archæological evidence: domestication is a shock to the physiology of man and beast. The skeletons of people change, they temporarily grow smaller and less healthy, as the human body adapts to a protein-poorer diet and a more arduous lifestyle. Likewise, newly domesticated animals get scrawnier at first.

But 8,000BC, it seems, was also the time when the local landscape began to alter. As the trees were chopped down, and the soil leached away, the area became arid and bare. What was once a glorious pastoral region of forests and meadows, rich with game and wild grasses, became a toilsome place that had to be worked ever harder.
http://www.forteantimes.com/features/articles/449/gobekli_tepe_paradise_regained.html

Unexplained 12,000 Year old Underground City
http://www.youtube.com/watch?v=3QfPQZtPgA0&feature=player_embedded