She spoke a pre-Inca language, Aymara, and through a translator I learned that she was explaining her success at feeding her kids for the first time in her life.

FORBES: Opportunity Collaboration: A New Kind of Business Retreat to Tackle Global Poverty

Although Peru has been a mining country since pre-Inca times, since 1992 output has tripled.

ECONOMIST: Big mining and its increasingly radical opponents

The railway involves a natural monopoly: the only other way of getting to the ruins is a four-day hike along the Inca Trail.

ECONOMIST: The battle to reach Machu Picchu

Sixteenth-century conquistadors cut a swath through ancient civilizations that had once rivaled those of the Aztec and Inca.

NPR: Unearthing History in 'A Voyage Long and Strange'

In fact, the Inca were a bit like Mitt Romney's Bain Capital: They had a knack for taking control of long-established things and making them their own.

CNN: 10 things to know before visiting Peru

Angkor Wat, a temple complex in Cambodia, and the Inca fortress of Machu Picchu in Peru (pictured above) are often cited as places of world-historical importance where a vast influx of tourists may be causing serious damage.

ECONOMIST: UNESCO is better at naming enemies than finding friends