Chankillo in Peru features 13 stone towers built in 250 to 200 BC that functioned as a calendar by marking the rising and setting arcs of the sun
Chankillo in Peru, which has been given Unesco world heritage status. Photograph: Ivan Ghezzi/Courtesy of World Monuments Fund
The Guardian-Dan Collyns in Lima
The oldest solar observatory in the Americas has been awarded Unesco world heritage status and dubbed “a masterpiece of human creative genius”.
The 2,300-year-old archaeological ruin Chankillo which lies in a desert valley in northern Peru was one of 13 new global sites added to the list of cultural monuments.
Thirteen towers that align on a ridge are the best-known feature of the ancient site which dates between 250 and 200 BCE. The towers functioned as a calendar using the rising and setting arcs of the sun to mark not only equinoxes and solstices but even to define the precise time of year to within one or two days. The site also includes an imposing triple-walled hilltop complex, known as the Fortified Temple set in the barren landscape of the Casma river valley.
Iván Ghezzi, the Chankillo programme director, told the Guardian that while he was “truly overwhelmed” by the recognition he was not surprised that the UN agency found Chankillo worthy of inclusion in the list.
“It is the only observatory from the ancient world that we know of that is a complete annual solar calendar,” said Ghezzi, an archeologist who has studied and worked on the site for two decades.
“The  towers are positioned in such a way that they match precisely the movement of the sun throughout the seasonal year from two very well-defined viewing points,” he said. “This has no parallels anywhere in the Americas or the world.”
Chankillo Photograph: Marice Castaneda/Courtesy of World Monuments Fund
“The ancient civilizations of Peru were practising the most sophisticated astronomy of the time,” he added.
The World Monuments Fund has been working with the Peruvian government and other organisations to protect the site for more than a decade.
“Its importance was relatively unknown, its deterioration was unaddressed, and protections were nearly nonexistent,” said Bénédicte de Montlaur, president and CEO of the fund.
“[This] announcement marks the progress of so many who worked tirelessly to safeguard this extraordinary heritage as the inheritance of all of humanity.”
Archeologists believe the site was likely abandoned in the early first century CE and was largely forgotten until the 19th century. No human remains have been found at the ruins and little is known about the culture.
“We know that it was built at a time of great conflict, great social strife,” said Ghezzi, explaining he believed the Chankillo society was the product of a process of “Balkanisation” following the collapse of the even older Chavín culture.
Chankillo is the third Peruvian site to be added to the Unesco world heritage list this century. The status was awarded to Qhapaq Ñan, a vast Inca road system in 2014, and to Caral, the oldest city in the Americas, in 2009.