Tiwanaku (Tiahuanaco)

Bayesian dating (102 AMS dates, Marsh 2012, Radiocarbon): site founded around AD 110 (50-170, 1σ). The peak of monumental construction is placed between AD 500 and AD 900, the collapse narrowed to ~AD 1010-1050 (95% CI). The pre-2012 consensus (occupation from ~300 BC) is revised.

Arthur Posnansky's dating (~17,000 BP, published in Tihuanacu: The Cradle of American Man, 1943) relied on assumed astronomical alignments of a building he had himself partly reconstructed. Refuted by stratigraphy, C14 and geomorphology (the 'lake shore' identified is a river valley wall). Kolata (1993), Janusek (2004) and Stanish (2002) treat it as historically null.

Documented materials: red sandstone (up to 131 tonnes, quarry ~10 km to the south); andesite (small blocks precisely cut, Copacabana peninsula on Lake Titicaca, ~90 km away). Protzen & Nair (1997, JSAH) document the tenon, mortise and groove system of the dry joints. Cramps of a ternary copper-arsenic-nickel alloy (Cu ~88%, Lechtman 1998) were hot-cast into channels carved into adjacent blocks.

UNESCO status: inscription no. 567, session 24, year 2000, criteria iii and iv. The site is recognized as the capital of a major Andean empire distinct from any other pre-Hispanic civilization in the Americas, attesting an exceptional political and ceremonial organization.

Estimated peak population (~AD 800): 10,000-20,000 inhabitants in the urban core (area ~4 km²) per the UNESCO consensus and World History Encyclopedia. Regional estimates reach 30,000-70,000 — a wide range, open debate.