Where is the archaeological site of Chankillo located?

Chankillo, also called Thirteen Towers of Chankillo, is an archaeological site erected between 200 and 300 BCE in the desert of the Sechín River basin in Peru. The site is about 9 miles (14 km) from the Pacific coast and consists of a hilltop building complex encircled by thick, gated walls, a row running north-south of 13 towers, and observation platforms on either side of the towers.

Chankillo had proven a mystery to explorers and archaeologists from at least the 19th century until the discoveries made in the 2007 study by Peruvian archaeologist Ivan Ghezzi and British archaeoastronomer Clive Ruggles. According to them, the placement of the 13 towers follows the arc of the shifting sun position as it sets and rises over the course of the six months between solstices. The sunrise on the summer solstices aligns with the northernmost tower when viewed from the observation point, and the sunrise aligns with the southernmost tower on the winter solstice.

The site shows great innovation by using the solar cycle and an artificial horizon to mark the solstices, the equinoxes, and every other date within the year with a precision of 1-2 days. It is thus a testimony of the culmination of a long historical evolution of astronomical practices in the Casma Valley.