In the beginning, there were the roaming alpacas, the bountiful green valleys that wound on forever, and the rising of a sun that was worshipped as a god.
When the Incas arrived at the Casma River Valley where a stone observatory once measured the passing of time using the sun, it must have seemed miraculous.
The Casma River Valley is a fertile haven amid unforgiving climates. It winds from Peru’s lush coast through arid deserts and rugged mountains, a thin ribbon of green carved through a vast tundra.
But although the Incas of Peru yoked the labor of slaves to till that bountiful valley, they did not build the solar observatory that stands there in ruins today. A crumbling complex called Chankillo, where said observatory rests, 250 miles north of Lima, preexists the reign of the Incan Empire by two millennia and was built by a more ancient people.
The Casma culture constructed Chankillo near the coast in the Casma Valley between 300 and 200 B.C. Here the solar observatory still tracks the path of the sun at different times of year with precision, despite being 2,300-years-old.
The still impressive stone structure is believed to have served as an ancient calendar.
How it works relates to its row of 13 stout stone towers evenly spaced upon a ridge, acting like a giant ruler. From a certain position a distance away, facing east toward the observatory, one can witness the sunrise along this row of towers.
Where exactly the sunrise appears between any two towers or at either ends of the row tells the observer the precise calendar date—the Casma culture did not use today’s Roman calendar, but a much older one, though both mark the solstices.
The solar observatory also marks the solstices.
The solstices are the longest and shortest days of the year, marking the start of winter and summer. Both the solstices also represent the extremes of the sun’s yearly sky path—northmost and southmost. A sunrise to the observatory’s left hand side, its northerly end, signifies the start of summer; rising to its right hand side, southerly end, means winter is here.
While a sunrise at either end of the observatory demarks the solstices, its appearing anyplace in the middle along this ruler of 13 towers corresponds to either of the two 6-month periods in between them.
Its measurements are accurate to within a day or two—no different from how the Casma culture read them eons ago. Today, this solar observatory is believed unique, and the oldest of its kind.
But that’s not all there is to Chankillo.
On a nearby hill, another impressive structure still stands: with triple walls for strength and false entrances to keep invaders at bay, a jumble of masonry in concentric loops is thought to be the vestiges of a fortified temple.
“Chankillo is a masterpiece of ancient Peruvians. A masterpiece of architecture, a masterpiece of technology and astronomy,” Peruvian archaeologist Ivan Ghezzi told AFP on a visit to the site. “It is the cradle of astronomy in America.”
In 2007, Mr. Ghezzi and his British colleague, Clive Ruggles, wrote a study on Chankillo. They proposed that the towers were a solar observatory that marked the solstices and may have helped ancient peoples keep track of the planting and harvesting seasons and religious holidays.
For a long time, the farmers of the modern-day Casama River Valley, and those along the fertile coast—who made Peru one of the world’s strongest producers of avocados—have looked to expand onto the lands where these archeological ruins stand.
In 2020, with the outbreak of COVID, archeologists abandoned many sites in Peru, and farmers reportedly capitalized on that by planting crops within the borders of Chankillo.
Since the pandemic began until now, dozens of historic sites have been cordoned off by UNESCO, including Chankillo and a number of other sites worldwide.
In 2021, Chankillo—along with Kaeng Krachan forest in Thailand and China’s ancient port of Quanzhou—was declared a restricted area and made a UNESCO World Heritage Site, reportedly to preserve what’s left of it while keeping farmers and looters away.
Another Peruvian site of ancient ruins was protected in 2009 when Caral, the oldest city in the Americas, along with six of its pyramids, became a World Heritage Site. Looking back decades further, the famous and soaring citadel Machu Picchu, high in the Peruvian mountains, has held protected status since 1983.
