"Gobekli Tepe
Gobekli Tepe is a Neolithic site in Turkey dating from about 9,000 BC to 8,000 BC, but some of the artifacts on the site go back to between 11,000 and 12,000 B.C. It pre-dates Stonehenge by 6,000 years and is the oldest known religious structure on Earth. The site, under excavation since 1994, contains 20 round structures four of which have been excavated. All in all it covers 22 acres.
Each round structure has a diameter of between 10 and 30 meters (30 and 100 ft) and all are decorated with massive, mostly T-shaped, limestone pillars that are the most striking feature of the site. The limestone slabs were quarried from bedrock pits located around 100 meters (330 ft) from the hilltop, using flint points to carve the bedrock. The pillars weigh 10-20 metric tons, with one found still in its quarry weighing 50 tons. That neolithic people with such primitive flint tools quarried, carved, transported uphill, and erected these massive pillars has astonished the archaeological world, and must have required a staggering amount of manpower and labor.
Archaeologists have identified two eras of construction, separated by thousands of years. The oldest era, starting around 11,000 years ago, contains the most elaborate carvings and attention to detail.
Adding to the enigma of the site is the fact that around 8000 to 7500 B.C. each enclosure was deliberately buried under as much as 300 to 500 cubic meters of debris consisting mainly of small limestone fragments, stone vessels, and stone tools; many animal, even human bones, are also found in the burial refuse. This, itself, was a monumental under-taking."