The World's Largest Monument Is Hidden Under A Mountain

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When Spanish explorer Hernan Cortéz conquered the Aztec city of Cholula in what is now Mexico, the settlers built a large church on the top of a hill as a symbol of their conquest. At least, they thought it was a hill. In reality, it was a massive pyramid, with a base 1,480 feet (450 meters) square and a peak 217 feet (66 meters) tall. By the time Cortéz and his army arrived, the pyramid—known as Tlachihualtepetl, or "man-made mountain"—was already a thousand years old and hidden under layers of dirt and overgrowth. In fact, according to legend, no one even knew it was a pyramid until construction began on an insane asylum in 1910. This is likely due to the fact that it was built from mud bricks, which combined with humidity to create a prime place for tropical plants to grow. With a base four times that of the Great Pyramid of Giza and twice the volume, Tlachihualtepetl isn't just the world's largest pyramid. It's the world's largest manmade monument, period. Learn more about the Aztecs in the videos below.

What Happened To The Aztecs?

Find out why this once great civilization disappeared.

Five Facts About The Aztecs

Learn some surprising things about this ancient culture.

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25 Things About Aztec Gods

Hear about why Aztec pyramids were built in the first place.

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