The pyramids of Teotihuacan are ancient structures located in the Valley of Mexico, built by a civilization that thrived between 100 BCE and 750 CE. The most notable pyramids are the Pyramid of the Sun and the Pyramid of the Moon, which served as religious and ceremonial sites. These pyramids are part of a larger urban center that includes temples, plazas, and residential areas. Teotihuacan was one of the largest cities in the ancient world, with a population of over 100,000 at its peak. The city is known for its unique architectural style and urban planning, influencing later Mesoamerican cultures. Today, it is a UNESCO World Heritage Site and a popular tourist destination.