Avant-garde German filmmaker Walter Ruttmann created the impressionistic "city symphony" movement when he released Berlin: Symphony of a City in 1927. A rhythmic, documentary-look at the city's industry and daily life, the film inspired a number of imitators. Before becoming an experimental filmmaker in the early '20s, Ruttman was a painter and an architect. In 1924, he helmed the dream sequence in Lang's Die Niebelungen, and two years later collaborated with Lotte Reiniger to create the first feature-length animated film, The Adventures of Prince Achmed. Following the success of Berlin, Ruttman made another city symphony film called World Melody in 1929. Ruttmann attempted a science fiction film, Steel, in 1933. In 1938, he helped edit Leni Riefenstahl's Olympia. During WWII, he made propaganda films for the Nazis.