Aztec New Year
The Aztec New Year (Spanish: Año Nuevo Mexicano or Año Nuevo Azteca; Nahuatl: Yancuic Xīhuitl, pronounced /ˈjaŋkʷik ˈʃiːwit͡ɬ/) is the celebration of the new year according to the Aztec calendar. The date on which the holiday falls in the Gregorian calendar depends on the version of the calendar used, but it is generally considered to occur at sunrise on March 12. The holiday is observed in some Nahua communities in Mexico. To celebrate, ocote (pitch-pine) candles are lit on the eve of the new year, along with fireworks, drumming, and singing. Some of the most important events occur in Huauchinango, Naupan, Mexico City, Zongolica, and Xicotepec.
The latest and more accepted version was proposed by professor Rafael Tena (INAH), based on the studies of Durán, Sahagún and Alfonso Caso (UNAM). His correlation confirms that the first day of the mexica year was February 13th according to the old Julian calendar or February 23rd of the current Gregorian calendar.
This 365-day calendar was corresponded with the solar year, was divided into 18 'months' of 20 days each, plus 5 'nameless' days at the end of the year. Also, there are some codices that show the existence of the leap year. 
- "El Observador #1 Bilingual Newspaper". El Observador. Retrieved 2012-12-07.
- "Inicia año nuevo Azteca". Oem.com.mx. Retrieved 2012-12-07.
- The Mexica Calendar and the Cronography, Rafael Tena. INAH-CONACULTA 2008.
- Folio 92r Codex Magliabechi (1553), Biblioteca Nazionale Centrale de Florencia: XIII, 3, 1996.
- Folio 7r Codex Telleriano-Ramensis (1562-1563), Bibliotheque Nacionale de France. Ms Mex 385, 1995.