The correct answer is - Mexico.
Teotihuacan is located near the capital of Mexico, Mexico city, just northeast of it. It is the biggest pre-Aztec archaeological site in the Mezoamerican region. This site is under the protection of UNESCO, and has the status of World Heritage Site.
Teotihuacan has lot to offer, and is a well preserved ancient site. It connects the temple of the supreme God Quetzalcoatl, with the Pyramid of Sun, and the Pyramid of the Moon. There's a museum specially dedicated for the findings from this site, and there's tons of pottery and bones that witness for the life at this place in the past.