Machu Picchu was build at the height of the Inca Empire around 1450 but abandoned just over a century later in 1572 after the Spanish arrival in Peru.
Archaeologists believe Machu Picchu was constructed for use as a Royal Estate.
Machu Picchu is located 2430 m (7970 ft) above sea level on a ridge between the Huayna Picchu and Machu Picchu mountains in Peru.
On July 24, 1911, American explorer Hiram Bingham III with the help of Melchor Arteaga, re-discovered Machu Picchu.
Bingham bought word of the ruins to the outside world. Only locals and a handful of missionaries and engineers had known of the site's existence.
It is believed Bingham was actually looking for a different 'lost' city, known as Vilcabamba.
Bingham's team excavated an estimated 40,000 artifacts to Yale University for further study including mummies, ceramics, silver statues, jewellery and bones. Peru has long wanted these artifacts back and an agreement was recently agreed for the majority of these items to be returned.
Since re-discovery over 30% of Machu Picchu has been reconstructed to give a better idea of how the original structures looked, restoration continues today.
In 1983, Machu Picchu became an UNESCO World Heritage Site. In 2007 it was voted one of the New Seven Wonders of the World in a worldwide Internet poll.
Machu Picchu was built in a typical Inca style, with beautiful, polished dry-stone walls of quarried granite stone.
The Incas were experts at using a building technique called ashlar in which blocks of stone are cut so precisely as to fit together tightly without mortar.
The incredible civil engineering techniques of the Incas reduced the affects of frequent earthquakes. Mortar-free walls, Trapezoidal, tilted inward and round corner doors and windows helped protect many of the buildings from collapsing.
It is estimated that 60% of the construction done at Machu Picchu was underground, including deep building foundations and crushed rock for drainage.
Machu Picchu's construction is amazing considering the Inca's did not use draft animals, iron tools, or the wheel. It's a mystery how the massive blocks of stone were moved up steep terrain and through dense bush, but it is generally believed that hundreds of men were used to push the stones up.
Machu Picchu had access to springs for water and enough terraced and irrigated land to grow food for around four times as many people as ever lived there.
The Machu Picchu site is divided in an urban area and an agricultural area. With an upper town area where royalty lived and temples built and a lower town area that included workers quarters and warehouses.
The Incas built a road to the Machu Picchu region and today thousands of tourists trek the 2-5 day high-altitude Inca Trail to visit Machu Picchu.
As Peru's most visited tourist attraction Machu Picchu is continually threatened by commercial forces. In the 1990s, the construction of a cable car, luxury hotel, and restaurants was allowed nearby. The Peruvian government has since set limits of a max of 2,500 visitors per day and only 400 visitors per day into the site.
