The other major Aztec calendar, the xiuhpohualli, is a solar calendar, based on 18 months of 20 days.

In the Aztec calendar, there are twenty day signs.

Images of pyramids, the "Aztec calendar", and armed indigenous warriors have been popular themes.

Tlaloc would require weeping boys in the first months of the Aztec calendar to be ritually murdered.

The carving, like the vampire's face, was straight out of an Aztec calendar.

Another huge piece was decorated with symbols of the Aztec calendar.

The Aztec calendar was related to their cosmology.

"And so far as we can tell, whoever this is has the timing down to correspond exactly to the Aztec calendar and no other."

It was celebrated a total of nine times, with the last one in 1507 (2 acatl by the Aztec calendar).

These total 52, the number of years on the Aztec calendar.