Mysteries surround the archaeological complex northeast of Mexico City whose pyramids—the Pyramid of the Moon and the even larger Pyramid of the Sun—remain popular tourist attractions.

(Getty Images)| In Mexico's ancient city of Teotihuacán – a UNESCO World Heritage Site that once boasted a population of more than 125,000 people – visitors will find the Pyramid of the Sun.

From exploring Mexico's diverse cities and magic towns ... its most impressive structure is by far the Pyramid of the Sun. The largest structure of its kind in the entire Western Hemisphere ...