Piedras del Tunjo (Spanish: Tunjo Stones) is an important archaeological park established on a natural rocky shelter 40 km west of Bogotá in the city of Facatativá. In ancient times it used to be the shore of a large lake flooding the Bogotá savanna. It was used by the Muisca rulers as a refuge during the time of the Spanish conquest. In fact, at this site the soldiers of Gonzalo Jiménez de Quesada killed the ruling zipa Tisquesusa in 1537. The huge rocks are covered with pictographs made by ancient settlers. They are estimated to be 10,000 years old.