Tiwanaku (Spanish: Tiahuanaco or Tiahuanacu) is a Pre-Columbian archaeological site in western Bolivia, near Lake Titicaca, about 70 kilometers from La Paz, and it is one of the largest sites in South America. Surface remains currently cover around 4 square kilometers and include decorated ceramics, monumental structures, and megalithic blocks. In AD 800 the site has been conservatively estimated to have been inhabited by 10,000 to 20,000 people.

The site was first recorded in written history in 1549 by Spanish conquistador Pedro Cieza de León while searching for the southern Inca capital of Qullasuyu.

Jesuit chronicler of Peru Bernabé Cobo reported that Tiwanaku's name once was taypiqala, which is Aymara meaning "stone in the center", alluding to the belief that it lay at the center of the world. The name by which Tiwanaku was known to its inhabitants may have been lost as they had no written language. Heggarty and Beresford-Jones suggest that the Puquina language is most likely to have been the language of Tiwanaku.