Machu Picchu, a ruined city once populated by Inca, was built in the 15th Century and remained hidden for half a millennium until a chance encounter brought the ruins back to the light of day.

Inca ruled what is now Peru for many years in the Middle Ages. One of the main centers of the Inca network was Cuzco, which was for a long time the capital of the Inca Empire. Machu Picchu was built in the early 15th Century, probably about 1450. Many people think that the city was built for an Inca emperor named Pachacuti.

Spanish conquistadors completed their conquest of the Inca in the late 16th Century. Machu Picchu is thought to have been abandoned in 1572. Spanish invaders plundered Cuzco but never found Machu Picchu.

For the next few hundred years, the stone walls of Machu Picchu sat abandoned and were gradually overgrown. That changed in 1911, when American archaeologist Hiram Bingham announced his discovery. Bingham had been searching for Vilcabamba, the last known Inca refuge from Spanish conquest. On July 24, 1911, Bingham followed the lead of a loyal Peruvian boy, who took him to the ruins not of Vilcabamba but Machu Picchu.

Since then, the "lost city" has been found by thousands of visitors each year. A Peruvian Historical Sanctuary and a UNESCO World Heritage Site, Machu Picchu was a winner in a 2007 worldwide Internet poll to name the New Seven Wonders of the World.

Archaeologists commonly divide the ruins into three groupings of stone walls: the Room of the Three Windows, the Temple of the Sun, and the Hitching Post of the Sun.

Today, Machu Picchu is a popular tourist destination, with about 2,500 people a day visiting the ruins.