I love movies from the silent era! One of my favorites is Metropolis...seriously one of the best sci-fi movies of all time (silent or not). The thing I love about silent films is that it makes them so much more accessible to foreign watchers. Metropolis originally had German intertitles, but because they are intertitles and not subtitles they're easily localized for other audiences. Unfortunately most of the films from the silent era are lost or destroyed.
Although speaking of Metropolis, one of my favorite anime films was based off of it (also called Metropolis).