The site is probably the most familiar symbol of the Inca Empire. Since 1983 the site has been designated as a UNESCO World Heritage Site, and has been the subject of concern about damage caused by tourism.

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 in 1532. Archeological evidence (together with recent work on early colonial documents) shows that Machu Picchu was not a conventional city, but a country retreat town for Inca nobility (similar to the Roman villas). The site has a large palace and temples to Inca deities around a courtyard, with other buildings for support staff. It is estimated that a maximum of only about 750 people resided in Machu Picchu at any one time, and probably only a small fraction of that number lived in the town during the rainy season and when none of the nobility were visiting.

It is thought that the site was chosen for its unique location and geological features. It is said that the silhouette of the mountain range behind Machu Picchu represents the face of the Inca looking upward towards the sky, with the largest peak, Huayna Picchu (meaning Young Mountain) representing his nose. The peak is also known as the "hitching post of the sun."

In 1913, the site received significant publicity after the National Geographic Society devoted their entire April 1913 issue to Machu Picchu.

In 2003, some 400,000 people visited Machu Picchu, and UNESCO has expressed concern about the damage this volume of tourism is causing to the site. Peruvian authorities insist that there is no problem, and that the remoteness of the site will impose natural limits on tourism [1]. Periodically, proposals are made to install a cable car to the site, but such proposals have so far always been rejected [2].

One of the Chilean poet Pablo Neruda's best-known works is "The Heights of Machu Picchu", inspired by the city:

"Machu Picchu es un viaje a la serenidad del alma, a la eterna fusión con el cosmos, allí sentimos nuestra fragilidad. Es una de las maravillas más grandes de Sudamérica. Un reposar de mariposas en el epicentro del gran círculo de la vida. Otro milagro más"

("Machu Picchu is a trip to the serenity of the soul, to eternal fusion with the cosmos, there we feel our own fragility. It is one of the greatest marvels of South America. A resting place of butterflies at the epicenter of the great circle of life. Another miracle.")

In 1981 an area of 325.92 square kilometres surrounding Machu Picchu was declared a "Historical Sanctuary" of Peru. This area, which is not only limited to the ruins themselves, also includes the regional landscape with its flora and fauna, highlighting the abundance of orchids.

The firmest theories maintain that it was an Incan "llacta": a settlement build up to control the economy of the conquered regions. It was the most beautiful llacta of the Incan empire, and would have been built with the specific purpose of protecting the most select of the Incan aristocracy in the event of an attack. It seems it was used in a particular moment as Zapa Inca's "resting place" and also as an "observatory". After the Spanish conquest, it was the stronghold of Manco Inca's revolt.

All of the construction in Machu Picchu uses the classic Inca architectural style of polished dry-stone walls of regular shape. The Incas were masters of this technique, in which blocks of stone are cut to fit together tightly without mortar. Many junctions are so perfect that not even a knife fits between the stones.

The Incas never used the wheel in any practical manner. How they moved and placed enormous blocks of stones is a mystery, although the general belief is that they used hundreds of men to push the stones up inclined planes. The Incas did not leave any documentation about that process because they did not possess a written language.

The space is composed of 140 constructions including temples, sanctuaries, parks and residences.

There are more than one hundred flights of stone steps – often completely carved in a single block of granite – and a great number of water fountains, interconnected by channels and water-drainages perforated in the rock, designed for the original irrigation system

Among the thousands of roads constructed by the pre-Columbian cultures in South America, the roads of the Inca were some of the most interesting. This network of roads converged at Cusco, the capital of the Inca Empire. One of them went to the city of Machu Picchu. The Incas distinguished between coastal roads and mountain roads, the former was called Camino de los llanos (road of the levels) and the latter was called Cápac Ñam.

Today, thousands of tourists walk the Inca roads – particularly The Inca Trail – each year, acclimatising at Cusco before starting on a two to four day journey on foot from the Urubamba valley up through the Andes mountain range.

Source: Wikipedia