Complex sentence: In the film, the building is said to have been designed by an insane architect named Ivo Shandor, who started a secret society which performed rituals on the building's roof as early as 1920.
Split into simpler sentences: In the film, the building is said to have been designed by an insane architect named Ivo Shandor. Shandor is said to have started his secret society, which performed rituals on the building's roof, as early as 1920.