Göbekli Tepe, located in southeastern Turkey, is considered the oldest temple in humanity's history, dating back about 11,500 years. Its discovery in the 1990s revolutionized archaeology because it contains enormous limestone pillars of up to 50 tons, carved with reliefs of wild animals, built long before the invention of writing, the wheel, or agriculture.
This site is decisive because it breaks the traditional theory that we first became farmers and then built temples. Göbekli Tepe suggests that it was religious fervor and the need to gather that drove hunter-gatherers to organize and, eventually, to invent agriculture to feed the workers. It is, essentially, the point where modern civilization was born.