'Lost City' No More, Machu Picchu Feels The Strain Of Booming Tourism

Peru's Machu Picchu — heralded as the "Lost City of the Incas" by American explorer Hiram Bingham, who rediscovered the largely forgotten site more than 100 years ago — has evolved into a tourist magnet.

Buses full of visitors regularly zigzag up and down the road that leads to this bucket-list destination built centuries ago, high in the Andes.

During the reign of the once-powerful Inca, the citadel was occupied by fewer than 1,000 people at any given time, according to historian Hugh Thomson, author of "The White Rock: An Exploration of the Inca Heartland."

Last year, more than 5,000 people on average walked the paths of Machu Picchu daily during the busiest months of July and August.

For the full story of why Machu Picchu feels the strain of booming tourism, click here.