Depending on you age you may have very different ideas of the story of Metropolis. There are at least three versions and at least as many authors. The original is of German origin and hit the theaters in 1927 as a silent movie. The second is Japanese, based very loosely on the first, and was created as a graphic novel in 1949. The third was based on the second and made into an anime movie in 2001.
All versions contain robots: androids actually. The German version features a female android named Maria who gets with the downtrodden working class humans and tries to start a class war. In Tezuka’s story, the android known as Michi leads a rise of the enslaved machines who no doubt represent the working class. In the 2010 anime the writer Katsuhiro Otomo featured fembot Tina who is a lot more dangerous than she looks.
Between the second and the third manifestation came a comic book and a 1960s cartoon series known as Astro Boy. This cartoon contains several of the main characters in the Metropolis novel although their roles were switched around a bit.
Oddly enough, Astro Boy as we know him does not appear in Tezuka’s Metropolis. There is an “artificial being” named Michi, who can change his gender from girl to boy. For the TV series Michi was split in half to give birth to Astro Boy and his sister Astro Girl. He also had at least one other sibling tossed in: supposedly a prototype of the final model.
Metropolis the anime movie also depicts the rift between the classes. Tina in this story combines elements of the previous two stories. In the 2010 Anime, Tina, the female robot is actually a weapon who hooks herself into the heart of a great building, which is the heart of the city and blows everything up. But after the great falling of civilization, the robots find pieces of Tina and begin to reassemble her.
To me, all three stories have the same societal message, and the same ending. All three stories depict robots and/or blue collar humans as downtrodden and being exploited by the upper classes. All three androids go up in a blaze of glory. There is also a unifying moral. When society has gone wrong, in order for a new one to emerge, the old one has to be torn down.