Secret of the Incas shot in Peru before. Wendell Corey was originally announced as star. In July 1953 Paramount took over Hal Wallis' contract with Charlton Heston and announced he would make the film after he finished "The Naked Jungle". "Secret of the Incas" was filmed on location in Peru at Cuzco and Machu Picchu, the first time that a major Hollywood studio filmed at this archeological site. A sixteen person unit including Heston, producer Mel Epstein and director Jerry Hopper spent a month filming footage in Peru in 1953. Five hundred indigenous people were used as extras in the film. The film also
Machu Picchu more farmland to grow crops, and to steepen the slopes that invaders would have to ascend. The terraces reduced soil erosion and protected against landslides. Two high-altitude routes from Machu Picchu cross the mountains back to Cusco, one through the Sun Gate, and the other across the Inca bridge. Both could be blocked easily, should invaders approach along them. The site is roughly divided into an urban sector and an agricultural sector, and into an upper town and a lower town. The temples are in the upper town, the warehouses in the lower. The architecture is adapted to the mountains.