Archaeologists have discovered a pyramid in southern Peru, built between 600 B.C. and 50 B.C. ago, would have aligned with two stone lines and the setting sun during the winter solstice. Here, a 3D model shows the event that happened at the Cerro del Gentil pyramid during the winter solstice. The two stone lines frame the pyramid with the sun setting directly behind it. This alignment may have had cosmological significance for the people who lived there.