San Andrés (formerly known as Campana San Andrés) is a pre-Columbian site in El Salvador, whose occupation began around the year 900 BC as an agricultural town in the valley of Zapotitán in the department of La Libertad. This early establishment was vacated by the year 250 because of the enormous eruption of the caldera of Lago Ilopango, and was occupied again in the 5th Century, along with many other sites in the valley of Zapotitán.