At a site called El Mirador in the crater of the Nevado de Toluca volcano, in central Mexico, INAH has found green beads, turquoise tiles and ceramics dating back to 1000 CE and earlier.
The crater was a meeting place for astronomer priests to predict the growing season. A Toltec fire container and pots with the possible image of Tlaloc have also been found. The material dates from the epi-Classic (650-900 CE) and Post-Classic (900-1200 CE).
The crater is geographically placed with two peaks behind it. The Sun passes through its zenith on May 16 and July 27 between these peaks and no shadow is cast there. Astronomers standing on the crater could calibrate the year and avoid the leap year problem.
El Mirador is the highest observatory in ancient Mexico. There are 17 sites in the vicinity of the crater that have been uncovered.
Source: INAH via sci.tech-archive [January 14, 2011]
