Puma Punku

H-blocks machined in andesite. The tool marks look like nothing from its century.

Part of Tiwanaku (Bolivia, c. 500-1000 CE): andesite and sandstone blocks cut with flat interior angles and repeated precision (the H-blocks) at 12,800 feet, by a culture without written records. Mainstream archaeology attributes them to skilled stone tools and templates; the machining appearance keeps it in the ancient-technology cluster with Baalbek and the Serapeum.