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The mystery of the Thirteen Towers of Chankillo

Thirteen towers march from north to south along the top of a low hill in the coastal Peruvian desert. These towers spread over 300 meters are part of a fourth-century BCE ceremonial complex in a remote location in Peru's Casma-Sechin River Basin.

Researchers have several ideas about what they were used for by these early Americans. Here are the facts about the towers. Can you use them to figure out what scientists have discovered?

The facts

  • The thirteen towers vary in size from 2 to 6 meters but are regularly spaced between 4.7 to 5.1 meters apart on the hill top.

  • Each tower has a pair of staircases on the north and south sides leading to the tower top.

  • The towers are surrounded by strong fortifications. There are thick walls, gates and parapets.

  • A group of buildings are 200 meters to the west and include a building with two courtyards and a 40-meter-long exterior corridor with an observing point. Archaeologists found offerings of pottery shells and other materials here, suggesting that people brought offerings to this spot when they viewed the towers.

What is it?

Researchers have believed the thirteen tower area was a fort, a ceremonial center or a fortified temple.

New studies by Ivan Ghezzi and Clive Riggles reveal that the thirteen towers are the oldest solar observatory in the Americas. It is 2,300 years old. From east and west observing points the towers mark the annual rising and setting arcs of the sun. They also serve as a calendar accurate to within a few days.

Studies of archaeological sites and written records show that the Incas were making careful solar observations by 1500 C.E. The thirteen towers complex provide evidence of earlier sophisticated sun cults than the Incans.