This sector, clearly separated from the previous one by a great perimetral wall, was accessed through a beautiful, double-jambed stone gateway - a typical feature of Inca architecture - giving access to the road from Cusco. This sector consists of 172 rooms of different shapes and sizes, communicated by 109 stairways enabling one to climb the steep hillsides.
The rooms are grouped as "districts", each with its specific function according to characteristic shapes and the cultural evidence from excavations.
For example, one sector was no doubt destined for storerooms for the corn or coca harvests from the agricultural terraces.
Another sector is more remarkable for the number of grain milling mortars (16) probably intended for production of chicha (corn beer) which is still widely used in the religious festivities in the Andes.
A third sector consists of homes of people who carried out specialized production activities, were in charge of religious ritual or agricultural labor.
Some of the rooms are outstanding for the fine finish of their walls, comparable to the exquisite buildings in Cusco, such as Coricancha or Acllahuasi. These were, perhaps, the most important buildings in this place.
The great plaza and the sacramental areas
The urban sector of living quarters is completed with the great central public plaza and two smaller ones. There are also some other buildings of an evidently ceremonial nature, that complete the urban sector.
Outstanding among these are the Temple of the Three Windows and the Intihuatana (5), a specially carved stone for making astronomical observations and chronological measurements. Here also is found a complex ritual system of baths and water fountains. Undeniably, Machu Picchu contains a series of buildings and viewing areas that shed light on Inca beliefs.
The citadel itself is an accurate reflection of their beliefs. It has a "U-shaped" ground plan. It consists of two series of buildings that lie on the edge of the precipice at either side of the plaza or Chaupipata, which has a north-south axis. The urban sector contains several temples, clusters of living areas and workshops.
Machu Picchu contains all the main buildings typical of a city, displaying the talents, skills and quality of the work produced by its pre-hispanic builders, since the stone used is all granite which is considerably harder than the building stone used in Cusco.