Mughal-E-Azam, one of the biggest films of Hindi Film Industry by K. Asif took 15 years to complete. The film was first announced in Mid 1945 on a grand scale. The star cast was a lot different than what we actually saw in the 1960 release.
The original cast had Nargis instead of Madhubala, Sapru instead of Dilip Kumar, Chandra Mohan instead of Prithviraj Kapoor, Veena instead of Nigar Sultana. Only Durga Khote was part of the original cast of 1945, who eventually played Jodha Bai in the final release. Anil Biswas was the first choice as music director, but later Naushad was roped in.
Dilip Kumar actually auditioned for the film in 1945 and was rejected.