Mesoamerican Civilizations and Territorial Planning

Mesoamerican civilizations developed sophisticated, cosmologically informed approaches to urban and territorial planning largely independent of Old World influence, reflecting their own distinct traditions of astronomical observation, agricultural adaptation, and monumental architecture. Teotihuacan, in the Basin of Mexico, grew by around 100–200 CE into one of the largest cities in the world at the time, with a population estimated at 100,000 to 150,000 at its peak (c. 300–500 CE), built around a rigorously orthogonal grid oriented roughly 15.5 degrees east of true north — an orientation long debated among archaeoastronomers but generally connected to sightlines toward the setting sun on specific calendrically significant dates and possibly to the heliacal rising of the Pleiades — and organized along the 2-kilometer-long central axis now called the Avenue of the Dead, anchored by the massive Pyramid of the Sun and Pyramid of the Moon.