From the top of my head:
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Paul Fejos' Lonesome (1928), the basic boy meets girl and they fall in love, but it's simple, silly, naive, beautiful. And it was done in a time when they were experimenting with sound and colour (stencils) and both the sound
(dialogue, sound, and song) and colour are so minimal and only appear when really necessary. It just melt my heart and I felt in love with this movie.
Trailer
https://youtu.be/tykxAt0UY8Y- and anything by
Josef von Sternberg, specially the Criterion Collection's
3 Silent Classics by Josef von Sternberg. Amazing movies, superb cinematography (I believe the best I have ever seen in silent era films).
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Metropolis has been mentioned but I would advise you to see the 2010 restored version as it is the most complete version. Before this restored version I never enjoyed the movie, I thought it was a boring mess and I couldn't understand what the "buzz" was all about Metropolis... and then I saw the restored version and my jaw dropped.