75 000-year-old Adam’s Calendar is Probably the World’s Oldest Man-Made Structure

Also referred to as “African Stonehenge,” Adam’s Calendar is a standing stone circle about 30 m in diameter in Mpumalanga, South Africa. Although uncertain, the structure is estimated to be 75 000 years old, making it the oldest man-made structure on Earth. Even though there are numerous astronomical alignments at the site, Adam’s Calendar is probably the only fully functional and almost intact megalithic stone calendar in the world.

Adam’s Calendar
Ancient Origins

According to the latest estimations, there are at least 100 000 stone circles throughout the mountains of South Africa. Known as the Birthplace of the Sun, this enigmatic site first draw public attention in 2003 when the South African pilot Johan Heine started photographing the region. The experts first thought that the ruins were the remains of cattle kraal (livestock enclosure) abandoned by the Bantu people around the 14th century. However, this suggestion seems unlikely as the usual materials of Bantu cattle-kraal structures comprised of thorny shrubs.

Screenshot from Google Earth showing only a small area in South Africa

There are at least 100 000 circular stone ruins scattered around the mountains of South Africa.

Bantu Cattle Kraal
Bantu Cattle Kraal by International Reads

In fact, Jehan’s discovery of the calender was accidental as a result of a plane crash. While looking for one of his pilots on the edge of a cliff, he noticed an arrangement of large stones. The placements of the stones are in alignment with the cardinal points as well as the equinoxes and solstices. By following the shadow of the sun, the calendar still functions today. According to archeologists, the calendar originally looked like the Stonehenge.

Adam’s Calendar

Experts made their first calculations based on the rise of the Orion constellation which is distinguishable for its three bright stars. The world moves on its axis, and the rotation completes a cycle about every 26,000 years. The astronomer Bill Hollenbach estimated the age of the ruin as at least 75 000 years by determining when the three stones in the calendar were in alignment with the three stars lined up against the horizon.

Adam’s Calendar
The African History

Further calculations based on both the rise of Orion and the erosion of the dolerite stones suggest that Adam’s Calendar is at least 160 000 years old.

Adam’s Calendar
Central Stones in the Adam’s Calendar by Atlas Obscura
Atlas Obscura