More than 11,000 years ago, hunter-gatherers built a monumental stone complex that is thought to be the world’s first temple. Known as Göbekli Tepe, the megalithic settlement is perched on a mountain ridge in Upper Mesopotamia, what is now southeastern Turkey. The Neolithic site, which translates to “belly hill” in Turkish, is two times older than Stonehenge and contains a series of elaborate circular enclosures constructed of massive T-shaped limestone columns. Many of the pillars feature intricate carvings of abstract symbols and wild animals, including lions, foxes, gazelles and birds.

For centuries, the structures remained hidden deep within the country’s Germuş mountains. Although originally discovered in the 1960s, the area was largely dismissed by researchers until the late German archaeologist, Klaus Schmidt, visited in 1994. Beginning excavations a year later, researchers discovered that hunter-gatherers were responsible for the site, since no domesticated plants or animals have been recovered. This discovery not only challenged what we thought we knew about ancient human civilizations but also revealed that hunter-gatherers were more than simply nomadic people. In fact, they were innovative enough to use advanced architectural techniques, such as using geometric patterns to mastermind and execute the construction.

Researchers consider the columns, which stand up to 18 feet (5.5 meters) tall and weigh as much as 50 tons (45 metric tons) each, to be architectural marvels. The structures were completed with only the tools available at the time, such as stone hammers and flint blades—which researchers have found strewn about the site during subsequent excavations. The monumental construction project also includes massive circular enclosures, a rainwater harvesting system and several smaller buildings.

“The architectural features stand out for their workmanship, size, stone working (such as the hewn floors) and sculpting,” says Gil Haklay, a doctor of philosophy with the Israel Antiquities Authority.

In 2020, Haklay published a study in the Cambridge Archaeological Journal that focused on the architectural planning used by hunter-gatherers to build Göbekli Tepe. Using computer modeling, his research revealed that workers relied heavily on geometry to construct the monolithic structures. Patterns soon emerged, leading researchers to conclude that the site was built as a single complex and not as individual structures added over the years.

“This was implied by the identification of a geometric pattern (based on an equilateral triangle) that regulated the position of the three enclosures and their architectural elements,” Haklay says.

The equilateral triangle, a shape that contains three sides of equal length, was built using three T-shaped pillars that align almost perfectly—connecting three temple-like enclosures. Haklay concluded that the builders may have stretched a piece of rope to the desired shape before constructing the columns to ensure their accuracy.

“Our research indicates that geometry was humanity's way of working things out,” he says.

However, one thing that researchers are less conclusive about is what the complex was used for. Some experts think it may have been used as a central location for people to gather for possible religious or ceremonial purposes. Because many hunter-gatherer societies were said to practice animism—the belief that all things, whether human, animal or plant, contain a soul—it’s possible that the site was a way for these people to come together and practice their beliefs. Since each pillar has its own unique animal carving, each enclosure could be a dedicated meeting site for different hunter-gatherer groups.

The abundance of animal carvings could also hint to something far more ritualistic or sinister, with some archaeologists speculating that the site could have been used for sacrificial purposes. Schmidt at one time speculated it could have been “a burial ground or the center of a death cult,” according to Smithsonian Magazine. He added that the dead would have the optimal view there, since “they’re looking out over a hunter’s dream.”

“Some of the architectural remains and small findings suggests cultic activity,” Haklay adds.

Fox remains were repeatedly discovered throughout the site and its likeness appears in numerous carvings. Further research is necessary to determine if this particular animal was worshiped by the hunter-gatherers who built the complex.

Perhaps we will never know the true origins of the site. However, since much of the location remains unexplored, it’s possible that future excavation could offer further evidence for the reasons ancient builders constructed Göbekli Tepe in the first place.