Mexico City

This expansive city of 20 million and over a mile high is built on the ruins of Tenochtitlan, the ancient Aztec capital.  Mexico City, called D.F. (for Distrito Federal; Federal District) or simply Mexico, is the capital, seat of government and the center of commerce, finance and the arts; in addition to being the largest city in the world.

The Zócalo has been the heart of Mexico city since the Aztecs’ rule. At the time of Moctezuma I this area was surrounded by palaces and temples, now it’s the second largest public square in the world (after the Red Square in Moscow). It’s official title is the Plaza de la Constitución; the word ‘zócalo’ means base or plinth and arose after a monument to Independence in the square was constructed only to that stage - then the name stuck.

Templo Mayor - This is the site of the Great Temple of Tenochtitlán, ancient capital of the Aztecs. Excavations were begun in 1978, when workmen discovered the Coyolzauhqui stone disc, weighing eight tons and marking the foot of the stairs of the temple. 
The Templo Mayor was destroyed by Hernan Cortés in 1521. It was center stage for the drama of Aztec ceremonial life. The temple served as the setting for colorful displays of highly-energized rituals depicting the relationships between temples and mountains, social groups, and humans and their gods.

UNAM Central Library
Built entirely of colored stones