This 7,000-year-old stone circle tracked the summer solstice and the arrival of the annual
monsoon season. It’s also the oldest known astronomical site on Earth.
For thousands of years, ancient civilizations around the world built huge stone circles to mark
the seasons and align them with the Sun and stars.
These early calendars predicted the arrival of spring, summer, fall, and winter, allowing
civilizations to prepare when to plant and harvest crops. They were also used as a sign of both
joy and sacrifice.

These megaliths — massive, ancient stone monuments — can seem enigmatic in our modern
era, when many people have no link to, or view of, the stars. Some also believe they are
mystical or divined by aliens.
However, several ancient civilizations kept time by observing which constellations rose at
sunset, similar to reading a massive celestial clock. Others also determined the position of the
Sun in the sky on the summer and winter solstices, the longest and shortest days of the year, or
the spring and fall lunar cycle.

There are approximately 35,000 megaliths in Europe alone, including several astronomically
aligned stone circles, tombs (or cromlechs), and other standing stones.
The majority of these structures were constructed between 6,500 and 4,500 years ago, mostly
along the Atlantic and Mediterranean coasts.
Stonehenge, a monument in England believed to be about 5,000 years old, is the most wellknown of these sites. Stonehenge, though still ancient, may have been one of Europe’s
youngest such stone structures at the time.
According to some historians, the regional practice of building megaliths first appeared along
the coast of France due to the chronology and drastic similarity between these widespread
European sites. It was then spread throughout the area, finally reaching the Great Britain.

However, even these primitive sites are centuries younger than the world’s oldest known stone
circle, Nabta Playa.
Nabta Playa is located in Africa, about 700 miles south of Egypt’s Great Pyramid of Giza. It was
built over 7,000 years ago, making Nabta Playa the world’s oldest stone circle — and probably

the world’s oldest astronomical observatory. It was built by a cattle-worshiping nomadic people
to commemorate the summer solstice and the arrival of the monsoons.
“Here is human beings’ first attempt to make some serious connection with the heavens,” J.
McKim Malville, a professor emeritus at the University of Colorado and archaeoastronomy
expert, tells Astronomy.

“This was the dawn of observational astronomy,” he adds. “What in the world did they think
about it? Did they imagine these stars were gods? And what kinds of connections did they have
with the stars and the stones?”

The Discovery of Nabta Playa
Egypt was preparing a massive dam project along the Nile River in the 1960s, which would
flood significant ancient archaeological sites. The United Nations Educational, Scientific, and
Cultural Organization (UNESCO) stepped in with funds to assist in the relocation of famous
structures as well as the search for new sites until they were lost forever.

But Fred Wendorf, a well-known American archaeologist, saw another possibility. He decided to
go beyond the Nile River in search of the ancient sources of Pharaonic Egypt.
“While everybody else was looking at temples, [Wendorf] wanted to look at the desert,” Malville
says. “He ushered in the predynastic period and the ancient kingdom.”
By chance, while crossing the Sahara in 1973, a Bedouin — or nomadic Arab — guide called
Eide Mariff came across a group of what appeared to be massive stone megaliths. Mariff drove
Wendorf, with whom he had collaborated since the 1960s, to the venue, which is about 60
miles from the Nile. Wendorf’s longtime friend and partner, Romuald Schild, recalls the
discovery tale differently. He claims that in 1973, the entire team was traveling through this
stretch of desert when they paused for a bathroom break. It was at this point that they
discovered traces of megalithic remains.
Wendorf initially mistook them for natural formations. However, he soon realized that the
location was once a huge lakebed, which would have ruined all such rocks. He would visit many
times over the next several decades. Wendorf and a team of excavators, including Polish
archaeologist Romuald Schild, then discovered a circle of stones that seemed to be aligned
with the stars in some enigmatic way during excavations in the early 1990s.