Yup. I finally saw this one. My town just recently hosted a screening with an extra half hour of missing footage, which I couldn't get tickets to, but I did watch a version that had placards to describe the parts we missed. However, there is still a bunch of dialogue I am convinced is missing.
This 1927 German film is absolutely legendary for it's class-concious message, dystopian style, visionary storytelling and amazing special effects for a movie of it's era. It's also inspired mny other films, including Blade Runner (1982) and the anime Metropolis (2001). The anime was based on a graphic novel by Osamu Tezuka from 1949, which was heavily influenced by the 1927 film. Square Enix's game Final Fantasy VII (1997) may have been inspired by the film or graphic novel.
All the themes are there: A class-concious "Utopian" society in which the ruling class above ground is not even aware of the existence of the working class below ground. Until one young man wanders below ground and sees the destruction, toil, and death. He falls in love with a prophetess who talks of a coming mediator - the heart (guess who that will be?) - until she is kidnapped and replaced by a
robot that looks just like her.
This is the movie that placed sci-fi on the map. It's very difficult to find an english version (the movie is originally German) and despite a post-WWI budget, the scenery is impressive, with many sets, and very extravagent models of both the city above ground, and the workers city below ground. Sometimes the vaudeville style of performance can be a distraction from the believability of the story, but for a black and white horror movie, it works. It takes a bit of effort to suspend disbelief, but it is possible and the payout is well worth it.
If the extended version hits your town, go check it out. But unless they announce that there will be an intermission, avoid drinks and bring adult diapers, because the version I watched was already two hours long. And think, even with the extra half-hour it is supposed that there is still anywhere from twenty to sixty minutes still unnacounted for. I hope that extra half-hour includes dialogue placards.