The Aztec calendar stone or Aztec Sunstone Calendar, carved in
basalt, is 3.6 meters (12 feet) in diameter and weighs about 24
metric tons. Containing images representing Aztec measurement of
days, months, and cosmic cycles, the stone was completed during
the 52 year period between 1427 and 1479 CE. It was originally
placed atop the main temple in Tenochtitlan, the capital of the
Aztec empire, facing south in a vertical position and was
painted a vibrant red, blue, yellow and white. When the
Spaniards conquered Tenochtitlan in 1521 they buried the stone,
and built the cathedral of Mexico City on the site. For over 250
years the stone was lost until December of 1790 when it was
excavated by accident during repair work on the cathedral. Today
it is located in the Museo Nacional de Antropologia, Mexico
City. "The stone was first described by the Mexican astronomer,
anthropologist and writer, Antonio de León y Gama in Descripción
histórica y cronológica de las dos piedras: que con ocasión del
empedrado que se est