The spectacular Incan city of Machu Picchu was thought to exist only in legend. Then in 1911, explorer Hiram Bingham III stumbled upon its remains high in the Andes Mountains. Although the site has been extensively studied, its purpose and function remain unclear. LOST CITY OF THE INCAS ventures to the peaks of South America to unravel the mysteries of this enigmatic city. Witness incredible footage of the earliest expeditions to Machu Picchu, and meet the men and women who have dedicated their lives to unearthing its history. Wander through the extraordinary ruins and sense the eerie presence of the past and the secrets that are purportedly locked somewhere within. Was the city a pleasure palace, an observatory, a fortress something else entirely? HISTORY takes viewers on an unforgettable journey into one of the most esoteric sites in the world.