Machu Picchu - civilization origins

Also known as the Lost City of the Incas

Machu Picchu is a mystery. There are several different theories as to how it came about and why it was found empty centuries later.
It was build in the 1400s, but remained unknown to the rest of the world until 1911. It was inhabited by Incas and is located 8,000 feet above sea level, and is in the midst of a tropical mountain forest on the eastern slopes of the Peruvian Andes.

Many theories about the reason the city was built suggest it was for an emperor and his family, though it has enough room for a small town. " Archaeologists have speculated that Machu Picchu was a temple or sanctuary for high priests and women who have been referred to as Virgins of the Sun, though more recent research has convinced many that it was built as an estate for the Incan emperor Pachacuti, who ruled from 1438 until 1471 or 1472."

The Incas probably chose this location because it is well-hidden, and when the Spanish conquerors invaded, they never found the civilization of Machu Picchu. With a plethora of stone available, they built the city: over 170 buildings and thousands of steps. They shaped stones out of the white granite so that they fit together so perfectly and tightly that one cannot stick a knife in between the stones. In addition, they did not have chisels, nor iron, and used river rocks to shape other rocks.

Along with all the buildings and steps, they build over 600 terraces on which they grew crops (likely maize and potatoes), and which kept the city from falling off the mountain. They build the terraces in layers: first a coarse rock base (which allowed water flow and stability), next they piled on smaller stones, a layer of gravel, a layer of sand, and finally a layer of soil on top.

They also had a sophisticated irrigation system, built 16 fountains, and received about 79 inchces of rainfall annually. The system is far too complex for me to summarize (or fully understand) other than saying: They build a series of canals and channels leading from a spring into the 16 fountains that they built. Their drainage system is similarly constructed but separated from the clean water for obvious reasons (wouldn't want any accidents when it comes to clean water). A more detailed description of the water system can be found here: http://www.waterhistory.org/histories/machu/