A recently discovered circular structure, below, made of red volcanic rock with a tree trunk in its center sits exposed at the archaeological site Templo Mayor in Mexico City, Friday, Oct. 5, 2012. ... more 
A recently discovered circular structure, below, made of red volcanic rock with a tree trunk in its center sits exposed at the archaeological site Templo Mayor in Mexico City, Friday, Oct. 5, 2012. Mexican archaeologists say they have uncovered the largest number of skulls ever found in one offering at the most sacred temple of the Aztec empire dating back more than 500 years, along with this circular structure which they believe may have been a sacred tree. (AP Photo/Alexandre Meneghini) less 
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Associated Press | Photo By Alexandre Meneghini
Fri, Oct 5, 2012 6:03 PM EDT