Chankillo

The site covers about four square kilometres (1.5 square miles) and has been interpreted as a fortified temple. The culture that produced Chankillo is called the Casma/Sechin culture or the Sechin Complex.

The regularly spaced thirteen towers were constructed atop the ridge of a low hill running near north to south, forming a "toothed" horizon with narrow gaps at regular intervals. To the east and west, investigators designated two possible 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, although not all of the towers are visible. On the winter solstice, the sun would rise behind the leftmost tower and then behind each of the towers in turn until it reached the rightmost tower six months later, on the summer solstice, marking the passage of time. Inhabitants of Chankillo would have been able to determine an accurate date, with an error of a day or two, by observing the sunrise or sunset from the correct tower. The Thirteen Towers could be the earliest known observatory in the Americas. A contemporary site in the Chincha Valley, Peru, of the late Paracas culture, which also marked the solstice, has recently been examined.