Klaus Schmidt, a member of the German Archaeological Institute, has found in Turkey a temple complex almost twice as old as anything comparable. "This place is a supernova," said Mr. Schmidt. "Within a minute of first seeing it, I knew I had two choices: go away and tell nobody, or spend the rest of my life working here."

The stone circles of Gobekli Tepe are his workplace since 1994.

Dated at about 9500 BCE, these stones are 5,500 years older than the first cities of Mesopotamia and 7,000 years older than Stonehenge.

 "Everybody used to think only complex, hierarchical civilizations could build such monumental sites and that they only came about with the invention of agriculture," said Ian Hodder, a Stanford University anthropology professor who has directed digs at Catalhoyuk,

"Gobekli changes everything. It's elaborate, it's complex, and it is pre-agricultural. That fact alone makes the site one of the most important archaeological finds in a very long time."