Fiery Roman Emperor Justinian ordered the rebuilding of the great church of Hagia Sophia in Istanbul almost 1500 years ago. Modern science now uncovers the secret to this vast golden dome's longevity.
Built using techniques that surpass modern ones, the temples, altars and residences of Machu Picchu have resisted torrential rains, landslides and earth tremors since being abandoned by the Incas.
Hidden deep in Cambodia's jungles, the temple of Angkor Wat is a towering monument to the Hindu god Vishnu, belying its origins as the mausoleum for a usurper king who murdered his great uncle.