Visitors tour Temple of Kukulkan, also called El Castillo ("the castle"), at Chichen Itza in Tinum, Yucatán, Mexico on Jan. 2, 1996.
© Mark M. Hancock / NewsEagles
Chichen Itza was a major Mayan city. Friday, Dec. 21, 2012 marks the end of the 13th b'ak'tun time period of the Mesoamerican Long Count calendar. This particular date had significance to the Mayan people.