Published: October 2006
Did You Know?
In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.

No, aliens did not design Teotihuacan, nor is it related to the lost city of Atlantis. Ever since the first aerial photographs of Teotihuacan were taken in the 1960s, the city's specific and precise layout has confounded scientists and scholars. The entire city is organized in a rigid grid system based on its central avenue, the Street of the Dead. This main street, however, is not oriented on a true north-south axis, but is offset by an exact 15.5º east of true north, a curiosity that has perplexed scholars and led to a variety of explanations throughout the years.

One of the more popular hypotheses suggests that the setting sun is at a 90º angle to the Street of the Dead on the days of the zenith (when the sun passes directly overhead). Some scholars, however, dismiss this hypothesis, stating that the math just doesn't add up. In the early 1970s, Colgate University astronomer and archaeologist Anthony Aveni suggested that a point 90º west of the Street of the Dead marked the setting position of the Pleiades, a star cluster linked to the Mesoamerican calendar, at about the time Teotihuacan was founded. However, Vincent Malmstrom, professor emeritus at Dartmouth College, argued a few years later that a point 90º west of the Street of the Dead marks the spot where, twice a year–on April 30 and August 13–the sun sets directly opposite the Pyramid of the Sun. Malmstrom believes this to be significant because the latter date is the day the ancient Maya believed the world began.

No conclusive explanation of why the founders of Teotihuacan oriented their city in such a specific way exists. Scientists and scholars are baffled and will, without a doubt, continue to look for clues to this one mystery among many that Teotihuacan holds.

—Agnieszka Siemiginowska