Deep in the Andean mountains lays a mysterious ruin named Machu Picchu. For 400 years it sat abandoned on its misty cliff, the quintessential lost city in the jungle. Rediscovered in 1911, it contained no written records or carvings, nothing that could shed light on its history. For a century since, it has defied the endless scores of visitors and scientists who attempted to understand its purpose. Who were the mysterious people who built it and why did they build it here? Today an international team of archeologists, engineers and scientists are finally piecing together the clues. Together they are discovering astonishing new burials, revealing the intricacies of its ingenious engineering and finally decoding the secrets of Machu Picchu.

• Documentary