How the Maya calendar works
Thousands of people are expected at Mexico's ancient sites for "end of the world" celebrations on 21 December, said to come from an ancient Maya calendar.
But modern day Maya say the reading of the calendar is wrong and the date simply marks the end of one cycle and the start of another.
Isidro Ek'mato owns a stall at the site of the Chichen Itza temple. He explained how to read the Maya calendar and how it fits in with the ancient religious site.