The Aztec calendar stone, Mexica sun stone, Stone of the Sun (Spanish: Piedra del Sol), or Stone of the Five Eras, is a large monolithic sculpture that was excavated in the Zócalo, Mexico City's main square, on December 17, 1790. It was discovered whilst Mexico City Cathedral was being repaired. The stone is around 12 feet (3.7 m) across and weighs about 24 tons.
The exact purpose and meaning of the stone is unclear. However archaeologists and historians have proposed a number of theories and it seems likely that there are many aspects to the stone.
Mexican anthropologist Antonio de León y Gama (1735-1802) remarked that the Sun Stone showed that the Aztecs had knowledge of geometry to be able to carve the stone symmetrically and it showed they also had knowledge of mechanics to be able to move the stone from its quarry to its final destination.
One aspect of the stone is its religious significance. One theory is that the face at the centre of the stone represents Tonatiuh, the Mexica god of the sun. It is for this reason that the stone became known as the 'sun stone'. Richard Townsend proposed a different theory, claiming that the figure at the centre of the stone actually represents Tlaltecuhtli, the Mexica sea or earth monster who features in Mexica creation myths. Another feature of the stone relates to time, hence the name 'calendar stone'. Some of the circles of glyphs are the glyphs for the days of the month. Further, some of the symbols may represent the five ages that the Mexica believed the earth had passed through. Yet another characteristic of the stone may be its geographic significance. The four points may relate to the four corners of the earth or the cardinal points. The inner circles may express space as well as time. Moreover, there is the political aspect of the stone. It may have been intended to show Tenochtitlan as the centre of the world and therefore as the centre of authority.
Despite being known as a 'calendar stone,' modern archaeologists such as those at the National Anthropology Museum in Mexico City, at which the stone is housed, believe it is more likely to have been used primarily as a ceremonial basin or ritual altar for gladiatorial sacrifices, than as an astrological or astronomical reference.
The calendar stone image has been adopted by modern Mexican and Mexican American/Chicano culture, and is used in folk art and as a symbol of cultural identity.
