Archaeologist Carlos Javier Gonzalez says the stone platform measuring 45 feet (15 meters) in diameter was probably built around 1469.
He says it could be the spot where Aztec emperors were cremated and buried.
Researchers have been on a five-year quest to find the tombs of Aztec emperors on the western edge of their main ceremonial center, now in downtown Mexico City. None has ever been located. Archaeologist Raul Barrera said Thursday that records written before the arrival of the Spanish indicate such platforms were the site of royal cremations.
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