An empire with no writing, no wheel and no money
At its height the Inca EMPIRE ran about 2,500 miles down the western side of South America and governed perhaps twelve million people. It did this without a writing system, without wheeled transport, without draught animals strong enough to pull a cart, and without currency.
Instead it ran on obligation. Subjects owed labour — the mita — rather than taxes in coin: so many days a year building ROADs, farming state land or serving in the army, recorded and rotated. The state stored the surplus in warehouses along the roads and redistributed it in bad years. It is an unusual arrangement and it worked well enough that the Spanish kept parts of the labour system in place for their own purposes.
The quipu is a record you can hold
A QUIPU is a cord with dozens or hundreds of knotted strings hanging from it. Position along the string gives place value, knot type gives the digit, and colour and ply carry further meaning. Trained specialists, the quipucamayocs, kept census figures, tribute owed and storehouse contents on them, and could read a knot record back years later.
Roughly a thousand survive. The numerical ones can largely be read; whether some also encoded narrative or language remains an open question, and a handful of recent finds have kept the question alive. Most were destroyed deliberately after the conquest, which means an empire's entire administrative archive exists as a few hundred bundles of string.
The stonework has no mortar and survives earthquakes
Inca masons cut blocks that fit so precisely a knife blade will not go between them, with no mortar at all, and some walls at Sacsayhuamán use stones weighing over a hundred tonnes with curved, interlocking faces. They were shaped by patient pounding with harder hammerstones rather than cut with iron tools, which the Incas did not have.
The joints are the point. Mortar-free walls of irregular interlocking blocks can shift during an earthquake and settle back, and Cusco's Inca foundations have repeatedly outlasted the colonial buildings put on top of them — the 1950 earthquake flattened much of the Spanish city while the Inca STONE walls beneath stood. Modern engineers have studied it seriously.
Machu Picchu was never lost
Hiram Bingham is usually credited with discovering it in 1911. Local farming families were living on the site and growing crops on the TERRACEs when he arrived; a boy led him up. Earlier visitors had left their names scrawled on the walls, and the place appears on a German map from 1874.
It was probably a royal estate for the emperor Pachacuti rather than a lost city, abandoned within a century of being built and simply never found by the Spanish. The rest of the grid holds the empire's working parts: the LLAMA as the only pack animal, the terraced MOUNTAIN slopes, the POTATO — domesticated in the ANDES, where thousands of varieties still grow — the MAIZE, the WEAVING that carried more status than GOLD, the CONDOR, CUSCO at the centre, the SUN TEMPLE, the PRIEST, the FESTIVAL calendar and the EMPEROR. Our mountains page covers the Andes themselves.