In 1549, a Spanish chronicler crossed the Andes and reached the ruins of a city near Lake Titicaca. He asked the local people who had built it. They told him the stones had appeared overnight — placed there by beings who came before the time of memory.

He believed they did not know. He may have been right.

Tiwanaku rose, flourished, and ended a thousand years before the Inca. It cut andesite with tolerances museums still measure. It fed a population of thirty thousand on land four kilometers in the sky. It traded with valleys five hundred kilometers away. And it left no name for itself that any later civilization preserved.

The city beside the lake.