Tiwanaku

Tiwanaku sat on the southern shore of Lake Titicaca at 3,850 metres, higher than most cities the world has ever built. From around 500 CE it grew from a lakeside settlement into the capital of a state that reached across the south-central Andes through colonies and trade rather than a single marching frontier. Its engineers worked stone with a precision that still draws attention: the Gateway of the Sun cut from one andesite block 2.8 metres tall, its lintel carved with 48 winged figures around a central Staff Deity; the H-profile blocks of Pumapunku fitted at hard right angles; the terraced Akapana platform and the walled Kalasasaya court. The economy underneath the monuments was raised-field farming, the “suka kollus” — soil mounded into long beds between water channels that buffered frost and held moisture, feeding 10,000 to 20,000 people on potatoes and quinoa in a basin where ordinary fields would freeze.

Around 1000 CE the rain failed. Sediment cores from the basin record a prolonged drought, the lake level dropped, and the channels and raised fields that the population depended on dried out. The leadership lost its grip, people drifted off the monumental core into smaller rural settlements, and by roughly 1100 CE the city was empty. The Aymara lordships rose on the same ground in the centuries that followed. When the Inca arrived, several hundred years after the abandonment, they did not inherit Tiwanaku — they found ruins and took them for a sacred origin place, telling that their creator Viracocha had made the first people there at Lake Titicaca and reading the standing stone figures as remnants of an earlier race. The city they revered had already been dead for centuries.