Aztec emperor Montezuma collected his treasures -- including gold, silver and sculptures -- during years of deadly conquests.
After the emperor was killed by his people, explorer Hernan Cortes and the Conquistadors fled Mexico, dumping the riches they'd stolen from the emperor into the street. Later, with a larger team, they returned and Cortes and his men searched the lands looking for the treasure but found nothing.
Some historians say the treasure remains where the Conquistadors dropped it -- underneath the city.
No one is absolutely certain that this treasure exists but many books, articles and websites exist on the story.
Legend goes that during World War II, Japan sent its war loot to the Phillippines.
The story goes that when the ship arrived in the Phillippines, a Japanese general named Tomoyuki Yamashita was assigne to hide the treasure in tunnels. It's said that after the war ended, Japan had the treasure returned but historians have never found credible proof that the stash ever existed.
ABC News' Claire Shipman, Cindy Smith and Olivia Sterns and The Associated Press contributed to this article.