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. It has been conservatively estimated that the site was inhabited by 10,000 to 20,000 people in AD 800.

A city on the high plateau

The dating of the site has been significantly refined over the last century. From 1910 to 1945, Arthur Posnansky maintained that the site was 11,000–17,000 years old based on comparisons to geological eras and archaeoastronomy. Beginning in the 1970s, Carlos Ponce Sanginés proposed the site was first occupied around 1580 BC, the site's oldest radiocarbon date. This date is still seen in some publications and museums in Bolivia. Since the 1980s, researchers have recognized this date as unreliable, leading to the consensus that the site is no older than 200 or 300 BC.

More recently, a statistical assessment of reliable radiocarbon dates estimates that the site was founded around AD 110 (50–170, 68% probability), a date supported by the lack of ceramic styles from earlier periods. Tiwanaku began its steady growth in the early centuries of the first millennium AD. From approximately AD 375 to 700, this Andean city grew to significance. At its height, the city of Tiwanaku spanned an area of roughly 4 square kilometers (1.5 square miles) and had a population greater than 10,000 individuals.

The growth of the city was due to its complex agropastoral economy, supported by trade. The society appeared to have collapsed around AD 1000; the reason for this is still open to debate. Recent studies by geologist Elliott Arnold of the University of Pittsburgh have shown evidence of a greater amount of aridity in the region around the time of collapse.

Monuments and construction

The structures that have been excavated by researchers at Tiwanaku include the terraced platform mound Akapana, Akapana East, and Pumapunku stepped platforms, the Kalasasaya, the Kantatallita, the Kheri Kala, and Putuni enclosures, and the Semi-Subterranean Temple. Some authors believe that the elites of Tiwanaku lived inside four walls that were surrounded by a moat. This theory is called "Tiwanaku moat theory". This moat, some believe, was to create the image of a sacred island.

The Akapana is a "half Andean Cross"-shaped structure that is 257 m wide, 197 m broad at its maximum, and 16.5 m tall. At its center appears to have been a sunken court. This was nearly destroyed by a deep looters excavation that extends from the center of this structure to its eastern side. Material from the looter's excavation was dumped off the eastern side of the Akapana. A staircase is present on its western side. The Kalasasaya is a large courtyard more than 300 feet long, outlined by a high gateway.

The Kalasasaya is located to the north of the Akapana and west of the Semi-Subterranean Temple. Within the courtyard is where explorers found the Gateway of the Sun. Since the late 20th century, researchers have theorized that this was not the gateway's original location. Near the courtyard is the Semi-Subterranean Temple; a square sunken courtyard that is unique for its north-south rather than east-west axis.

Regional power and sacred space

The Tiawanaku culture increased its power in the Titicaca basin in the period 200-500 AD, reaching a peak in 500-600 AD. The people of Tiwanaku held a tight relationship with the Wari culture. The Wari and Tiwanaku civilizations shared the same iconography, referred to as the "Southern Andean Iconographic Series". The relationship between the two civilizations is presumed to be trade based or military based. The Wari aren't the only other civilization that Tiwanaku could have had contact with. Inca cities also contained similar types of architecture Infrastructure seen in Tiwanaku.

The architectural comparisons suggest that the Inca took some inspiration from the city of Tiwanaku and other early civilizations in the Andean basin. In many Andean cultures, mountains are venerated and may be considered sacred objects. The site of Tiwanaku is located in the valley between two sacred mountains, Pukara and Chuqi Q’awa. At such temples in ancient times, ceremonies were conducted to honor and pay gratitude to the gods and spirits. They were places of worship and rituals that helped unify Andean peoples through shared symbols and pilgrimage destinations.

Tiwanaku became a center of pre-Columbian religious ceremonies for both the general public and elites. For example, human sacrifice was used in several pre-Columbian civilizations to appease a god in exchange for good fortune. Excavations of the Akapana at Tiwanaku revealed the remains of sacrificial dedications of humans and camelids.