Home | Incas | Pre-Inca Chankillo and the Thirteen Towers. Satellite Image: Google Earth, Eye alt 5814 ft.

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Chankillo or Chanquillo is an ancient monument complex in the Peruvian coastal desert. The ruins include the hilltop Chankillo Castillo, the nearby Thirteen Towers and residential and gathering areas. The Thirteen Towers were proposed to have been a solar observatory built in the 4th century BC. in the March 2, 2007, issue of Science.

The Thirteen Towers of Chankillo (see the illustration above) course north to south along a ridge of a low hill and are regularly spaced, forming a "toothed" horizon with narrow gaps at regular intervals. To the east and west investigators found two observation points. From these vantages, the 300m long spread of the towers along the horizon corresponds very closely to the rising and setting positions of the Sun over the year. This infers that some activities of the ancient civilization may have been regulated a solar calendar.

Ancient solar observatory found in Peru

Friday, 2 March 2007. Source: Reuters by Maggie Fox


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.

Ghezzi and colleagues say they have figured it out.

"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.

"In the five-hour drive to the towers I could see that he was a little sceptical," Ghezzi says.

"When he got there and made a few measurements he realised that from the points we were showing him, the alignments worked out perfectly."

Ruggles, co-author on the paper, says often such claims do not pan out. But this one did.

"The fact that, as seen from these two points, the towers just span the solar rising and setting arcs provides the clearest possible indication that they were built specifically to facilitate sunrise and sunset observations throughout the seasonal year," he says.

Ghezzi says little is known of the people who built Chankillo. They pre-date the Incas by centuries.

But he is not surprised that such an ancient observatory was discovered.

"Peru is one of the unexplored archaeological frontiers in the world," he says.

He is also not surprised by the sophistication.

"The astronomical knowledge behind Chankillo could have been maintained by much simpler means," Ghezzi says.

"This kind of knowledge is essential for survival: to navigate, to follow animals and be able to come back to the place of your origin, to keep track of seasons. We have to find other reasons to explain why a group of people would go to such great lengths as to construct such monumental towers on top of a hill."

There is much evidence to show the Incas used the Sun's movements for political demonstrations of power.


Towers point to ancient Sun cult

The oldest solar observatory in the Americas has been found, suggesting the existence of early, sophisticated Sun cults, scientists report.

March 1, 2007 Source: BBC News

It comprises a group of 2,300-year-old structures, known as the Thirteen Towers, which are found in the Chankillo archaeological site, Peru.

The towers span the annual rising and setting arcs of the Sun, providing a solar calendar to mark special dates.

The study is published in the journal Science.

Clive Ruggles, professor of archaeoastronomy at Leicester University, UK, said: "These towers have been known to exist for a century or so. It seems extraordinary that nobody really recognised them for what they were for so long.

"I was gobsmacked when I saw them for the first time - the array of towers covers the entire solar arc."

The Thirteen Towers of Chankillo run from north to south along the ridge of a low hill within the site; they are relatively well-preserved and each has a pair of inset staircases leading to the summit.

The rectangular structures, between 75 and 125 square meters (807-1,345 sq ft) in size, are regularly spaced - forming a "toothed" horizon with narrow gaps at regular intervals.

About 230m (750ft) to the east and west are what scientists believe to be two observation points. From these vantages, the 300m- (1,000ft-) long spread of the towers along the horizon corresponds very closely to the rising and setting positions of the Sun over the year.

"For example," said Professor Ruggles, "if you were stood at the western observing point, you would see the Sun coming up in the morning, but where it would appear along the span of towers would depend on the time of the year."

"So, on the summer solstice, which is in December in Peru, you would see the Sun just to the right of the right-most tower; for the winter solstice, in June, you would see the Sun rise to the left of the left-most tower; and in-between, the Sun would move up and down the horizon."

This means the ancient civilization could have regulated a calendar, he said, by keeping track of the number of days it took for the Sun to move from tower to tower.

Sun cults

The site where the towers are based is about four square kilometres (1.5 square miles) in size, and is believed to be a ceremonial centre that was occupied in the 4th Century BC. It is based at the coast of Peru in the Casma-Sechin River Basin and contains many buildings and plazas, as well as a fortified temple that has attracted much attention.

The authors of the paper, who include Professor Ivan Ghezzi of the National Institute of Culture, Peru, believe the population was an ancient Sun cult and the observatory was used to mark special days in their solar calendar.


Stone Towers Are Decoded as Earliest Solar Observatory in the Americas

Ancient Peruvians built towers to track arc of sun

March 6, 2007 Source: The New York Times by John Noble Wilford

Early people in Peru, like others in antiquity, went to great lengths to track the rising and setting of the sun through the seasons as a guide for agriculture, an object of worship and a mystical demonstration of a ruler’s power.

Archaeologists have now discovered that a line of elaborate stone towers erected on a low ridge by Peruvians 2,300 years ago formed an artificial toothed horizon with narrow gaps at regular intervals for making alignments almost exactly spanning the annual arc of the sun.

This is the earliest known solar observatory in the Americas. The site precedes by several centuries similar monuments by the Maya in Central America and by almost two millenniums solar observatories of the Inca civilization in Peru.


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. When viewed from the western observation point, the Sun appears to the left of the left-most tower.



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Last updated: March 11, 2007