History's Greatest Mysteries

With 500-year-old secrets hidden in skeletons and stone, Machu Picchu remains one of the most puzzling archaeological sites on earth; it ranks among the ancient world's most enduring riddles, pertaining to its creators and reason for its creation.

The story of the most celebrated warrior king in history still stirs fascination more than 2,000 years after his death. But the location of his body is the subject of much debate. When his remains suddenly disappear without a trace, a search across the ancient world ensues. What happened to the mummy of Alexander the Great?