This is a small copy of the Aztec sun stone.
The Aztec sun stone (Piedra del Sol in Spanish) is a late post-classic Mexica sculpture housed in the National Anthropology Museum in Mexico City, and is perhaps the most famous work of Aztec sculpture. The stone is 358 cm in diameter and 98 cm thick, and it weighs about 21.8 tonnes. 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.
(Source: Wikipedia)
