Machu Picchu, Peru
The ancient citadel of the Incas -- also called the Lost City of the Incas -- is perched 7,900 feet above in the mountain jungles of the Andes, near the Amazon basin. It is considered one of the most mysterious sights in the world. And it is man-made.
For nearly 500 years it remained hidden.
It was built around 1450 AD very close to the Inca capital. Hardly 50 years later, the Inca kingdom was conquered by Spanish adventurers. Machu Picchu for some reason escaped the notice of the Spaniards and the jungle swallowed it up. It was re-discovered by American explorer Hiram Bingham in 1911.
Some facts you probably did not know:
In 1913, National Geographic magazine, which funded Bingham's expedition, dedicated an entire issue to Machu Picchu.
Peru's top tourist site is not faring well under the tourist stampede and UNESCO has deemed it at risk.
Bingham, a professor at Yale university, was led to Machu Picchu by a local who knew of its existence. It is believed a missionary duo had discovered the site a decade or so earlier.
Photograph: Alejandra Brun/AFP/Getty Images