10 hour clock (Motif)
Lang's world revolves around a clock that has ten hours, not twelve like we are accustomed to. The clock is built this way because the workers in the workers' city work ten hour days. We see the clock several times throughout the film, and the motif of time reminds us that the world of Metropolis is built around long and oppressive work days. It also reminds us that the narrative takes place in an imagined future.
Workers' City (Symbol)
Most of the locations in the film are symbolic of the status of their inhabitants. The workers' city is far beneath the surface of the earth, where there is no light. Given its location beneath the crust of the earth, the workers' city is a symbol of a lifeless place, where people are cut off from pleasure and light, and must work to find purpose in the world. The depth of the city represents the workers' low position on the class ladder.
The Garden (Symbol)
In contrast to the workers' city is the garden in which we first meet Freder, situated high above the city in a high rise among the clouds. The garden is a symbol of the upper classes' life which is free from hardship. Its position high in the sky represents how those who are from the upper classes have an elevated and privileged position in society.
Tower of Babel & Religious Symbolism (Allegory)
The Tower of Babel, a story from the Bible about a giant tower that stretched into the heavens and was built by exploited laborers, is a consistent reference point in the film, and serves as an allegory that illuminates many of Metroplis' themes. The city of Metropolis is a modern Tower of Babel, in which the laborers are exploited to make the city what it is, so that the members of the upper classes can live lavish and worry-free lives. The biblical implications are such a strong undercurrent in the film that when Freder visits the workers' city and witnesses a machine explode, he hallucinates that the machine is a giant mouth of an ancient biblical God, Moloch, swallowing up the workers.
Robot Maria (Symbol)
When the Machine-Man is endowed with Maria's facial characteristics and programmed to destroy the city, she becomes a kind of symbol for sin and indulgence, a whore of Babylon, and a debased, sinful creature. She gyrates and dances in a sexually manipulative way and causes the men around her to devolve into chaos because of her seductive ways. The robotic manifestation of Maria becomes a symbolic entity, a witch-like representation of all of society's ills, a chaotic and disorganizing entity of unbridled desire that creates chaos and ruination wherever she goes.
