Map - Teotihuacán

Teotihuacan (Spanish: Teotihuacán) is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, 40 km northeast of modern-day Mexico City. Teotihuacan is known today as the site of many of the most architecturally significant Mesoamerican pyramids built in the pre-Columbian Americas, namely the Pyramid of the Sun and the Pyramid of the Moon. At its zenith, perhaps in the first half of the first millennium (1 CE to 500 CE), Teotihuacan was the largest city in the Americas, considered as the first advanced civilization on the North American continent, with a population estimated at 125,000 or more, making it at least the sixth-largest city in the world during its epoch.

The city covered eight square miles (21 km2), and 80 to 90 percent of the total population of the valley resided in Teotihuacan. Apart from the pyramids, Teotihuacan is also anthropologically significant for its complex, multi-family residential compounds, the Avenue of the Dead, and its vibrant, well-preserved murals. Additionally, Teotihuacan exported fine obsidian tools found throughout Mesoamerica. The city is thought to have been established around 100 BCE, with major monuments continuously under construction until about 250 CE. The city may have lasted until sometime between the 7th and 8th centuries CE, but its major monuments were sacked and systematically burned around 550 CE. Its collapse might be related to the extreme weather events of 535–536.

Teotihuacan began as a religious center in the Mexican Highlands around the first century CE. It became the largest and most populated center in the pre-Columbian Americas. Teotihuacan was home to multi-floor apartment compounds built to accommodate the large population. The term Teotihuacan (or Teotihuacano) is also used to refer to the whole civilization and cultural complex associated with the site.

Although it is a subject of debate whether Teotihuacan was the center of a state empire, its influence throughout Mesoamerica is well documented. Evidence of Teotihuacano presence is found at numerous sites in Veracruz and the Maya region. The later Aztecs saw these magnificent ruins and claimed a common ancestry with the Teotihuacanos, modifying and adopting aspects of their culture. The ethnicity of the inhabitants of Teotihuacan is the subject of debate. Possible candidates are the Nahua, Otomi, or Totonac ethnic groups. Other scholars have suggested that Teotihuacan was multi-ethnic, due to the discovery of cultural aspects connected to the Maya as well as Oto-Pamean people. It is clear that many different cultural groups lived in Teotihuacan during the height of its power, with migrants coming from all over, but especially from Oaxaca and the Gulf Coast.

After the collapse of Teotihuacan, central Mexico was dominated by more regional powers, notably Xochicalco and Tula.

The city and the archeological site are located in what is now the San Juan Teotihuacán municipality in the State of México, approximately 40 km northeast of Mexico City. The site covers a total surface area of 83 km2 and was designated a UNESCO World Heritage Site in 1987. It is the most-visited archeological site in Mexico, receiving 4,185,017 visitors in 2017.

The name Teōtīhuacān was given by the Nahuatl-speaking Aztecs centuries after the fall of the city around 550 CE. The term has been glossed as "birthplace of the gods", or "place where gods were born", reflecting Nahua creation myths that were said to occur in Teotihuacan. Nahuatl scholar Thelma D. Sullivan interprets the name as "place of those who have the road of the gods." This is because the Aztecs believed that the gods created the universe at that site. The name is pronounced in Nahuatl, with the accent on the syllable wa. By normal Nahuatl orthographic conventions, a written accent would not appear in that position. Both this pronunciation and the Spanish pronunciation are used, and both spellings appear in this article.

The original name of the city is unknown, but it appears in hieroglyphic texts from the Maya region as puh, or "Place of Reeds". This suggests that, in the Maya civilization of the Classic period, Teotihuacan was understood as a Place of Reeds similar to other Postclassic Central Mexican settlements that took the name of Tollan, such as Tula-Hidalgo and Cholula.

This naming convention led to much confusion in the early 20th century, as scholars debated whether Teotihuacan or Tula-Hidalgo was the Tollan described by 16th-century chronicles. It now seems clear that Tollan may be understood as a generic Nahua term applied to any large settlement. In the Mesoamerican concept of urbanism, Tollan and other language equivalents serve as a metaphor, linking the bundles of reeds and rushes that formed part of the lacustrine environment of the Valley of Mexico and the large gathering of people in a city.

As of January 23, 2018, the name Teotihuacan has come under scrutiny by experts, who now feel that the site's name may have been changed by Spanish colonizers in the 16th century. Archeologist Veronica Ortega of the National Institute of Anthropology and History states that the city appears to have actually been named Teohuacan, meaning "City of the Sun" rather than "City of the Gods", as the current name suggests.