The Aztec civilization settled in central Mexico in 1325 and built the great city of Tenochtitlan before being conquered by the Spanish in 1521. They created their own calendar, known as the Aztec Sun Calendar, which was carved in stone and consisted of 20 symbols representing a 260 day cycle used to predict rituals and events. While the Aztec and modern calendars both tell the days and have cycles, the Aztec calendar was used for forecasting whereas today's calendar only tracks the days, though the Aztec calendar evolved into the common calendar in use today.