Tiwanaku and Puma Punku
500–900 CE (mainstream); some researchers claim older
The ruins of Puma Punku at Tiwanaku, Bolivia, contain H-shaped stone blocks weighing up to 800 tonnes, cut with such precision that they interlock like machine-made parts. The andesite used was quarried 90 kilometres away. The blocks show drill holes and straight cuts that appear to require metal tools and machinery that did not exist in pre-Columbian South America.