Cuzco was the ancient capital of the empire and remains the modern Peruvian center in the Andes. It was fortified by the structure of Sacsahuaman on a hill above the city.
This amazing construction was built from about 1438 A.D. to 1500 A.D. It consists of three tiers of large limestone blocks that protect the highest point on which was a palace of the Inca and two large watchtowers that overlooked the city. These fortifications in the captial can be used to deduce the militaristic nature of the empire. Security from marauding Amazonian tribes was a concern.
The construction at Sacsahuaman is absolutely astonishing.The stones were quarried about 20 kilometers away and transported to the site by human power. The largest stone weighs approximately 20 tons (see illustration below). Several stones that "got away" from the construction teams are evident along the bottom of the ravine on the way to the quarry. Sacsahuaman is known to have employed about 30,000 workmen over a period of seventy years. The contstruction was part of the not-to-distant history of the Inca at the time of the conquest and was recorded by early Spanish chroniclers.
The towers were torn down after the conquest and their blocks were used in construction.
Incredible as it seems now, the blocks from ancient, mostly Incan, ruins were used with governmental encouragement for new construction into the 1940's. Since then, the ruins have been recognized for what they are: a truly impressive testament to the organizational and engineering skills of a pre-industrial human society.
Besides the three great walls, at the top of the hill and overlooking the city of Cuzco, the foundation of one of the towers has been uncovered.