I'll use the Wikipédia explanation to make a resume about this place
Machu Picchu is one lost city of the Inca Empire, It is one of the most important archaeological centers in South America and as a consequence the most visited tourist attraction in Peru.
Let’s talk about the history of this place…
Machu Picchu is probably the most familiar symbol of the Inca Empire. It is thought that the city was built by the Sapa Inca Pachacuti, starting in about 1440, and was inhabited until the Spanish conquest of Peru. Archaeological evidence shows that Machu Picchu was not a conventional city, but a country retreat town for Inca nobility. The site has a large palace and temples dedicated to Inca deities around a courtyard, with other buildings for support staff.
Machu Picchu is located 70 kilometers to the northwest of Cusco, on the crest of the mountain Machu Picchu, located about 2,350 meters above sea level. From the top, at the cliff of Machu Picchu, one can appreciate the vertical precipice of 600 meters ending at the foot of the Urubamba River. The location of the city was a military secret because its deep precipices and mountains were an excellent natural defense.
According to the archaeologists, Machu Picchu was divided in three great sectors: the Sacred District, the Popular District, to the south, and the District of the Priests and the Nobility (royalty zone).
All visits to Machu Picchu at some point leave from Cusco, which can be reached via a domestic flight from Lima, or international flight from La Paz, in Bolívia. Taking the tourist train from Cusco (which takes 3.5 hours to get to Machu Picchu), you have several options.
The most common way is to take the train to Machu Picchu in the morning, explore the ruins for a few hours and return to Cusco in the afternoon. The train terminates at Puente Ruinas station, where buses take tourists up the mountain to Machu Picchu.
Another option is to hike the Inca Trail, on either a four-day or two-day version, both of which are controlled by the government. They require travelers to be reasonably fit. The trip takes a few days, and involves sleeping in tents.
Another option is to stay overnight near the ruins themselves, rather than return on the same day. There are many hotels at nearby Aguas Calientes, or the more expensive Machu Picchu Sanctuary Lodge, the only hotel located at Machu Picchu itself.
all the content of this post you can find at: http://en.wikipedia.org/wiki/Machu_Picchu