The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

A backdoor to Machu Picchu that only the most foolhardy infiltrator would attempt to breach.

It took 82 years and four different plaques to finally get the story right.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.