This image of the Aztec calendar wheel — also known as the Stone of the Sun — that was excavated in the Zócalo (main square) in Mexico City comes from Drogdon’s photostream. The basalt stone is about twelve feet in diameter. It is now in the collections of the National Museum of Anthropology, Mexico City.
It’s possible that this is a photo of a replica, as it doesn’t look sufficiently aged to be the real stone. (If anyone knows, please leave a comment.)