Gobekli Tepe in Turkey, which challenges preconceived notions about the development of civilization, was constructed 6,000 years before Stonehenge by an ancient population.

German archaeologist Klaus Schmidt was confident the structures he discovered were exceptional, if not unique, when he initially started digging on a Turkish mountaintop 26 years ago.

Schmidt found more than 20 circular stone enclosures atop the Gobekli Tepe, or "Belly Hill," a limestone plateau near Urfa. The largest, a circle of stone with two ornately carved pillars standing 5.5m tall in the middle, measured 20 meters across. Up to 10 tons of stone were carved into creepy, stylized human figures with folded hands and fox-pelt belts. For people who hadn't yet domesticated animals or created pottery, let alone metal tools, carving and erecting them must have been a major technological difficulty. The constructions were 11,000 years old, or more, making them humanity's oldest known massive structures, created not for shelter but for some other reason.

Following ten years of research, Schmidt came to an amazing conclusion. Schmidt, who was then working for the German Archaeological Institute, told me Gobekli Tepe may assist rewrite the history of civilization by illuminating the reasons why people first started farming and establishing permanent settlements when we visited his dig house in Urfa's old town in 2007.

The circular enclosures were created by hunter-gatherers who were surviving off the land as humans had since before the last Ice Age, according to the stone tools and other evidence Schmidt and his team discovered at the site. There was no trace of domesticated grains or other plants, and the tens of thousands of animal bones discovered were from wild species.

Schmidt hypothesized that these hunter-gatherers had gathered together 11,500 years ago to use stone tools to carve the T-shaped pillars at Gobekli Tepe, quarrying limestone from the hill beneath their feet.

It would have been a huge work to carve and move the pillars, albeit possibly not as challenging as it first appears. The bedrock of the hill's natural limestone layers served as the material for the pillars. Given enough practice and patience, limestone is soft enough to be worked with the flint or even wood tools of the time. Archaeologists studying at the site believe that rather than cutting away the extra from underneath as well, ancient builders simply had to do so since the limestone formations on the hill were horizontal layers between 0.6m and 1.5m thick. Using rope, log beams, and plenty of labor, they moved the carved-out pillar a few hundred meters over the mountaintop.

Schmidt believed that the region's small, nomadic bands were driven by their religious convictions to regularly band together on the hilltop for construction projects, hold large feasts, and then disperse once more. Schmidt asserted that rather than being a village, the location was a center for rituals, possibly a complex for burial or death cults.

That was a bold assertion. Complex ritual and organized religion were long believed by archaeologists to be luxury items that societies only acquired once they started domesticating plants and animals, a period known as the Neolithic. The idea was that once they had a surplus of food, they could use their excess resources for rituals and monuments.

Schmidt informed me that Gobekli Tepe reversed that timeline. Radiocarbon readings and the presence of stone tools at the site clearly dated it to the pre-Neolithic period. There has been more than 25 years since the initial digs, and no signs of domesticated plants or animals have been found. Furthermore, according to Schmidt, nobody was residing there permanently. A "cathedral on a hill," he described it as.

If such were the case, it would demonstrate that elaborate ritual and social organization predated settlement and cultivation. Over a period of a thousand years, the requirements of bringing together nomadic bands in one location to carve and move enormous T-pillars and build the circular enclosures compelled people to proceed to the next stage, which was to domesticate plants and animals to make food supplies more predictable and dependable in order to regularly host large gatherings. It seems that ritual and religion started the Neolithic Revolution.

The following morning, before dawn, Schmidt and us drove to the mountaintop. As Schmidt led a small group of German archaeologists and workers from the small village down the road, we roamed, mystified and in awe, amid the pillars. Schmidt's head was wrapped in a white cloth to shield it from the scorching sun.

The previous year, Schmidt had just released his initial studies on Gobekli Tepe, which had stirred up the small community of Neolithic archaeology specialists. Although there were temporary corrugated steel roofs covering the excavation sections and potholed dirt roads going up to the hilltop dig site from the valley below, the location still had a drowsy, abandoned feel to it.

When they were first released in the mid-2000s, Schmidt's interpretation of the site's remarkable T-pillars and huge, spherical "special structures" enthralled colleagues and media. Breathtaking media accounts referred to the location as the "cradle of religion," and the German magazine Der Spiegel compared the lush plains nearby to the Garden of Eden.

Consequently, tourists from all over the world flocked to Gobekli Tepe to view it for themselves. Within ten years, the hilltop underwent a complete transformation. Work on the site frequently slowed to a crawl as busloads of curious tourists crowded around open excavation trenches to see what some were calling the world's first temple and made it impossible to maneuver wheelbarrows on the narrow paths until the nearby Syrian civil war disrupted tourism in the area in 2012.

The mountaintop outside of Urfa has once more changed shape during the last five years. Today, highways, parking lots, and a visitor center can hold curious tourists from all over the world. In 2017, modern, swooping fabric and steel shelters covering the main monumental buildings took the place of corrugated steel sheds. One of Turkey's biggest museums, the Anlurfa Archaeology and Mosaic Museum was established in 2015 in the heart of Urfa. It includes a full-scale replica of the site's largest enclosure and its imposing T-pillars, allowing visitors to experience the site's colossal pillars and study their carvings up close.

Turkish tourist officials proclaimed 2019 the "Year of Gobekli Tepe" and used the historic monument as the centerpiece of their international marketing campaign after Gobekli Tepe was inscribed on the Unesco World Heritage List in 2018. Jens Notroff, an archaeologist with the German Archaeological Institute who started working at the site as a student in the mid-2000s, recalled it as "still being a secluded area on a mountainside." "It's entirely changed."

Schmidt, who passed away in 2014, was unable to see the site's evolution from a dusky mountaintop dig to a popular tourist destination. The Neolithic transition, however, was sparked by Schmidt's finds there, and in recent years, fresh information from Gobekli Tepe and a closer examination of the findings from earlier digs have overturned Schmidt's early interpretations of the location.

Archaeologists had to go deeper than Schmidt ever had to work on the foundations required to hold up the site's sweeping cloth canopy. A team from the German Archaeological Institute worked under the guidance of Schmidt's successor, Lee Clare, and dug multiple "keyhole" trenches to the site's bedrock, which was several meters below the floors of the massive buildings. Clare remarked, "We got a rare opportunity to go explore at the lowest levels and deposits of the site.

What Clare and his colleagues discovered might yet again rewrite prehistory. The excavations turned up signs of homes and year-round habitation, indicating that Gobekli Tepe wasn't just a remote temple that people visited on rare occasions but rather a vibrant village with a focal point of enormous special structures.

The crew also discovered hundreds of grinding implements for processing grain for use in brewing beer and cooking porridge, as well as a sizable cistern and canals for collecting rainwater, both essential for sustaining a town on the parched hilltop. Gobekli Tepe remains a singular, exceptional site, but the latest revelations mesh better with what we already know from other sites, according to Clare. "It was a whole settlement with ongoing habitation. It has completely altered how we perceive the website."

Turkish archaeologists have located at least a dozen additional hilltop sites with comparable, albeit smaller, T-pillars from the same time period in the rough terrain surrounding Urfa. According to Barbara Horejs, a researcher at the Austrian Archaeological Institute who specializes in the Neolithic and was not involved in the most recent research work, "It's not a unique temple." "It greatly increases the story's interest and excitement." Mehmet Nuri Ersoy, the minister of culture and tourism in Turkey, went so far as to call this region the "pyramids of south-east Turkey."

Clare and others now believe that Gobekli Tepe was an attempt by hunter-gatherers to cling to their fading lifestyle as the world changed around them rather than a centuries-long building project spurring the switch to farming. Evidence from the area suggests that people were experimenting with domesticated animals and plants at other places, a development the residents of "Belly Hill" may have been opposing.

The stone carvings at the location, according to Clare, are a crucial cue. Gobekli Tepe's pillars and walls are covered in intricate carvings of foxes, leopards, serpents, and vultures, which he described as "not animals you see every day." "They're more than simply photographs; they're narratives, which are crucial for forming a shared identity and for keeping people together."

We recall a sense of immense distance when we initially stumbled upon the site more than 15 years ago. Gobekli Tepe, which was constructed 6,000 years before Stonehenge, has engravings whose precise meaning, like the previous world in which its inhabitants lived, is incomprehensible.

Of course, that contributes to the Gobekli Tepe's extraordinary magnetism. Researchers will keep working to figure out why it was created in the first place as thousands of visitors wonder at a location that most people had never heard of ten years ago. The information we now know about the location and the history of human civilization is expected to change with each new discovery.

The new work, according to Horejs, "stands on Klaus Schmidt's shoulders rather than undermining his theory." "I believe there has been a significant increase in knowledge. Science is all about changing interpretations, after all."