The legendary 'Lost City of Machu Picchu‘, located high in the Peruvian Andes, is without a doubt the most important tourist attraction in Peru and one of the world's most impressive archaeological and civil engineering sites.
The original entrance to the complex is on the southwestern side of the citadel at the end of the Inca Trail, a short walk away from "Intipunko " (Sun Gate), the ancient final check point to Machu Picchu.
The present entrance on the southeastern side leads to the agricultural section.
The central plaza that separates the religious from the urban section, has a great rock in the center. The religious section contains splendid architecture and masonry works. One of the most important and enigmatic is probably the Intihuatana shrine, this block of granite was presumably used to make astronomical observations.
In the southern part of this section are found a series of niches carved on rock known as "the jail" with elements that include man size niches, stone rings would have served to hold the prisoner's arms, and underground dungeons.
The largest urban section in Machu Picchu is located on the north western part. It is reached by a 67 steps staircase and involves a group of buildings not as finely constructed as other parts of the complex.
Huayna Picchu, young peak, is as much a part of the site as the buildings of the citadel, the towering granite peak overlooks Machu Picchu to the North with a steep well preserved original Inca path, well worth the one hour climb for an astounding view of the citadel and the entire valley.
There was no ‘urban sprawl’ in this mountain retreat of about 1,000 residents; thoughtful consideration was made before the first stone was cut.
The placement of the residence of the Inka (the title of the ruler is used today to name the people) was determined by the location of the mountain spring.
The Inca engineers built the canal at a slope that allowed gravity to pull the water at just the speed they desired for the city’s use, then they used that information to place the royal residence, as well as, the city.
The canal descends the mountain slope, enters the city walls, passes through the agricultural sector, then crosses an inner wall into the urban sector, where it feeds a series of 16 fountains known as the stairway of fountains.
The fountains are publicly accessible and partially enclosed by walls that are typically about 1.2 m high, except for the lowest fountain, which is a private fountain for the Temple of the Condor and has higher walls.
View of terraces and rain channels from thatched hut.
Perhaps the most visually striking features of the drainage system are the agricultural terraces. Machu Picchu includes 4.9 ha of agricultural terraces, which are held in place by stone retaining walls. In addition to maximizing the land available for farming, the terraces also protected the agricultural sector from erosion.
Wright conducted soil analyses that showed that the Inca constructed the terraces with subsurface drainage in mind. The Inca layered each terrace for efficient drainage, with a layer of stones at the bottom, followed by gravel, sandy material, and topsoil.
In the 15 th century, the buildings in the urban sector would have been covered with thick thatched roofs.
Because of the density of buildings with impermeable roofs, Wright estimated that about 60% of the water yield from the urban area would have occurred as surface flow.
The Inca constructed their plazas in the same way as the terraces, with a deep subsurface layer of rock chips. The plazas received runoff from other areas of Machu Picchu, and the subsurface layer of rocks helped the water to penetrate the ground quickly. Plaza Drainage
Machu Picchu's well-designed drainage infrastructure is one of its most remarkable secrets. It is also one of the keys to its longevity, says Wright: "They built for permanency. They didn't do anything halfway."
At Machu Picchu, drainage was a serious problem. The site rested on top of a ridge with a roughly 50 percent slope and received almost 2,000 mm of rainfall.
For their city to endure, the Inca had to find a way to keep it from sliding down the mountain.
Flooding is controlled by two methods:
1 st a level area of the canal is designed to overflow into a terrace field for irrigation;
2 nd was an overflow outlet by fountain 4 and the main stairway (like slue-ways on modern civil engineering projects).