Even this aerial shot of the Teotihuacan pyramid doesn't show how huge it is; it's massive.

It's one of the first big cities in the Western Hemisphere.

The Pyramid of the Sun was built by an unknown cultural group sometimes simply called the Teotihuacanos.

They built it by hand over a thousand years before the Aztecs showed up in central Mexico.

The Aztecs, also known as the Mexicas, later discovered it and gave it its name.