Discovery of the Aztec calendar stone.
The Aztec sun stone (Spanish: Piedra del Sol) is a late post-classic Mexica sculpture housed in the National Anthropology Museum in Mexico City, and is perhaps the most famous work of Mexica sculpture. It measures 358 centimetres (141 in) in diameter and 98 centimetres (39 in) thick, and weighs 24,590 kg (54,210 lb). Shortly after the Spanish conquest, the monolithic sculpture was buried in the Zócalo, the main square of Mexico City. It was rediscovered on 17 December 1790 during repairs on the Mexico City Cathedral. Following its rediscovery, the sun stone was mounted on an exterior wall of the cathedral, where it remained until 1885. Early scholars initially thought that the stone was carved in the 1470s, though modern research suggests that it was carved some time between 1502 and 1521.