"The City of the Gods", Teotihuacan was built around 200 A.D. by the Teotihuacans using astronomical observations. A powerful city state in central Mexico it peaked with 150,000 inhabitants around 600 A.D. It was probably the largest city in Mesoamerica. The city continued until 750 A.D. Today is one of the most beautiful archaeological sites in Mexico. The site is listed as a UNESCO World Heritage Site.
The Earth and Its Peoples A Global History, Bulliet et al, 2005.