CALENDAR STONE: 25-ton, 4 m (13-feet) wide carved monolith commissioned by the Emperor Axayacatl in 1479, which symbolizes the Aztec universe. The populations of central Mexico believed that they were living in the fifth epoch of a series of worlds (or suns) marked by cyclical generation and destruction. The central figure of the stone is this fifth sun, Tonatuih. Surrounding this are four rectangular cartouches containing the dates and symbols for the gods Ehecatl, Texcatlipoca, Tlaloc, and Chilchihuitlicue who represent the four worlds previously destroyed and the dates of the previous holocausts – 4 Tiger, 4 Wind, 4 Rain, and 4 Water. The central panel contains the date 4 Ollin (movement) on which the Aztecs showed that they anticipated that their current world would be destroyed by an earthquake. In a series of increasingly larger concentric bands, symbols for the 20 days of the month, precious materials, and certain stars are represented. The outermost band depicts two massive serpents whose heads meet at the stone’s base. The Calendar Stone is in the Museo Nacional de Antropología (National Museum of Anthropology) in Mexico City.