The Göbekli Tepe site is believed to be a social or ritual compound dating back to the 10th–8th millennium BCE. Circles of massive T-shaped stone pillars were erected in what appears to be ritualistic structures and are known as the world’s oldest known megaliths. More than 200 pillars in about 20 circles are currently known through geophysical surveys. Each pillar has a height of up to 20 ft and weighs up to 20 tons. They are fitted into sockets that were hewn out of the bedrock. In later periods the erected pillars are smaller and stand in rectangular rooms with floors of polished lime.
The details of the structure’s function remain a mystery. It was excavated by a German archaeological team under the direction of Klaus Schmidt from 1996 until his death in 2014. Schmidt believed that the site was a sanctuary where people from a wide region periodically congregated, not a settlement.
The site was first noted in a survey conducted by Istanbul University and the University of Chicago in 1963. American archaeologist Peter Benedict identified lithics collected from the surface of the site as belonging to the Aceramic Neolithic, but mistook the stone slabs (the upper parts of the T-shaped pillars) for grave markers, postulating that the prehistoric phase was overlain by a Byzantine cemetery.
The hill had long been under agricultural cultivation, and generations of local inhabitants had frequently moved rocks and placed them in clearance piles, which may have disturbed the upper layers of the site. At some point, attempts had been made to break up some of the pillars, presumably by farmers who mistook them for ordinary large rocks.
In 1994, Klaus Schmidt of the German Archaeological Institute, who had previously been working at Nevalı Çori, was looking for another site to excavate. He reviewed the archaeological literature on the surrounding area, found the 1963 Chicago researchers’ brief description of Göbekli Tepe, and decided to reexamine the site. Having found similar structures at Nevalı Çori, he recognized the possibility that the rocks and slabs were prehistoric. The following year, he began excavating there in collaboration with the Şanlıurfa Museum and soon unearthed the first of the huge T-shaped pillars.