Description: Travelers have noticed the 13 stone towers rising over Peru's coastal desert since at least the nineteenth century. But researchers only last year discovered the structures' purpose: they make up a sophisticated solar observatory, one of the earliest known in the Americas.
IvŠn Ghezzi of Peru's National Institute of Culture and Clive Ruggles of the University of Leicester showed that the arc of the 13 Towers of Chankillo, built by a still unnamed culture, corresponds almost exactly to the rising and setting sun's range of movement over a year. On the December 15 solstice, for example, the sun would have risen directly over the southernmost tower, when viewed from the west. Wooden lintels embedded in the towers date to about 300 B.C.
Tracking the sun's progress would have helped Chankillo's builders time the planting of their crops. But the towers were probably also meant to express rulers' mystical kinship with the sun, and their ability to influence its movement. "If you were just measuring seasons, there would be no need to make such great structures," says Ghezzi. "The idea was to transmit a political and ideological message about a ruler's close relationship with the sun." An enormous, circular "fortress" near the towers may have played a role in the display.