Machu Picchu - Cusco Region, Peru - Height: 2,430 meters - Completion Year: Estimated to be in the mid-15th century - Construction Cost: Incalculable

Detail: Machu Picchu is an ancient Incan citadel perched high in the Andes, known for its advanced engineering and breathtaking views.

Interesting Fact: It remained undiscovered by the Spanish conquistadors and was only revealed to the world in 1911.