Built around the mid 15th century, Machu Picchu is a (3) (a)   example of the Inca's engineering feats

The Inca (4) (a)   Machu Picchu's palaces, temples, terraces, and infrastructure using stone and without the help of wheels or tools made of steel or iron.

Nonetheless, the stones of Machu Picchu were cut so (5) (a)   that they snugly fit together.

These engineering marvels have (6) (a)   Machu Picchu's remarkable condition for over 500 years.

Machu Picchu's (7) (a)   is still a mystery to many archeologists.

But in the early 16th century, only about 100 years after it was built, Machu Picchu was (8) (a)   , and since the Inca had no written language, no records exist to explain the exact purpose of the site.

Arteaga, a local farmer (9) (a)   Machu Picchu to outsiders when he led Yale University professor Hiram Bingham to the site.

Despite its enigmatic nature, Machu Picchu still stands as one of the world's most important (10) (a)   sites.

In (11) (a)   , UNESCO designated Machu Picchu as a world heritage site and today visitors from around the world come to pay homage to this piece of history.

The stone city of Machu Picchu is one of the most fascinating archeological sites on the planet. (1) (a)   northwest of Cuso, Peru, Machu Picchu is a testament to the power and ingenuity of the Inca people.