Puebla, Mexico: Great Pyramid of Cholula
What looks like a grassy hill in the modern Mexican state of Puebla is actually one of the world’s largest ancient monuments, a pyramidal complex covering nearly 45 acres and rising 177 feet high. Its formal name is Tlachihualtepetl, but many people simply call it the Great Pyramid of Cholula. It was built in stages by pre-Columbian people and was once used by the Aztecs as a temple to their god Quetzalcoatl. After the city’s conquest by Spanish colonizers in the 16th century, a Catholic church was erected on the top of the grass-covered pyramid.