The Teotihuacan is an ancient Mesoamerican city located in the Basin of Mexico, just 30 miles northeast of modern-day Mexico City. It was one of the largest cities in the pre-Columbian Americas, and was home to an estimated population of 125,000 people
From Wikipedia
Teotihuacan is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, 40 kilometers (25 mi) northeast of modern-day Mexico City.