Machu Picchu is comprised of approximately 200 buildings, most being residences, although there are temples, storage structures and other public buildings. It has polygonal masonry, characteristic of the late Inca period.
About 1,200 people lived in and around Machu Picchu , most of them women, children, and priests. The buildings are thought to have been planned and built under the supervision of professional Inca architects. Most of the structures are built of granite blocks cut with bronze or stone tools, and smoothed with sand. The blocks fit together perfectly without mortar, although none of the blocks are the same size and have many faces; some have as many as 30 corners. The joints are so tight that even the thinnest of knife blades can't be forced between the stones. Another unique thing about Machu Picchu is the integration of the architecture into the landscape. Existing stone formations were used in the construction of structures, sculptures are carved into the rock, water flows through cisterns and stone channels, and temples hang on steep precipices.
The Incas planted crops such as potatoes and maize at Machu Picchu . To get the highest yield possible, they used advanced terracing and irrigation methods to reduce erosion and increase the area available for cultivation. However, it probably did not produce a large enough surplus to export agricultural products to Cuzco, the Incan capital.
One of the most important things found at Machu Picchu is the intihuatana, which is a column of stone rising from a block of stone the size of a grand piano. Intihuatana literally means ‘for tying the sun", although it is usually translated as "hitching post of the sun". As the winter solstice approached, when the sun seemed to disappear more each day, a priest would hold a ceremony to tie the sun to the stone to prevent the sun from disappearing altogether. The other intihuatanas were destroyed by the Spanish conquistadors, but because the Spanish never found Machu Picchu , it remained intact. Mummies have also been found there; most of the mummies were women.
Few people outside the Inca’s closest retainers were actually aware of Machu Picchu existence. Before the Spanish conquistadors arrived, the smallpox spread ahead of them. Fifty percent of the population had been killed by the disease by 1527. The government began to fail, part of the empire seceded and it fell into civil war. So by the time Pizarro, the Inca’s conquerer, arrived in Cuzco in 1532, Machu Picchu was already forgotten.
Machu Picchu was rediscovered in 1911 by Hiram Bingham, a professor from Yale. Bingham was searching for Vilcabamba, which was the undiscovered last stronghold of the Incan empire. When he stumbled upon Machu Picchu , he thought he had found it, although now most scholars believe that Machu Picchu is not Vilcabamba. Machu Picchu was never completely forgotten, as a few people still lived in the area, where they were "free from undesirable visitors, officials looking for army ‘volunteers’ or collecting taxes", as they told Bingham.