A line of 13 stone towers discovered on a hillside in Peru forms part of an ancient solar observatory that had a major role in society centuries before the Incas, scientists say.
The 2300-year-old site, the oldest in the Americas, points to a sophisticated culture that used the dramatic alignment of the Sun and the structures for political and ceremonial effects, the researchers write today in the journal Science.
The site, called the Thirteen Towers of Chankillo, precisely spans the annual rising and setting arcs of the Sun when viewed from two specially constructed observation points.
“Thousands of people could have gathered to watch impressive solar events. These events could have been manipulated for a political agenda,” says lead author Ivan Ghezzi.
He made the discovery while a graduate student at Yale University and is now archaeological director of the National Institute for Culture in Peru.
For instance, at the time of the summer solstice, the longest day of the year, the Sun rises just to the left of the northernmost tower, Ghezzi says.
Chankillo is a large ceremonial centre laid out over several square kilometres. It has a heavily fortified hilltop structure, thick walls and parapets.
But no one quite understood a 300-metre-long line of towers that sits on a nearby hill like spines on a dragon’s back. “Since the 19th century there was speculation that the 13-tower array could be lunar demarcation. But no one followed up on it,” Ghezzi says.
He tested the idea while studying military structures at the site, which dates to the 4th century BC. But it took him several years to contact Professor Clive Ruggles, of the University of Leicester, a leading UK authority on archaeoastronomy, for verification.