F.W. Murnau's 1927 classic (which you can also read as "so damn old only critics and film historians have heard of it") "Sunrise" is now available in the public domain from Archive.org. Murnau is best known as the director of "Nosferatu," and the formative influence on cinema as a whole that's visible in both of these films is astonishing. Murnau was German, but this is an American film - his first shot in the U.S.
Our leads are a love triangle: a married man (credited as "The Man," played by George O'Brien), his wife ("The Wife," Janet Gaynor) with whom he has a child, and "The Woman From the City" (Margaret Livingston). The movie is a comedy-drama, with the man initially convinced to murder his wife, but forced to spend time with her and remembering why he loved her. Murnau does some really lovely cinematography, somewhat weakened by the faded movie print, but you can see it must have been great at release. He messes with the intertitles, sometimes having them blur and twist to indicate moods (something I haven't seen before, although I guess that doesn't mean too much). He overlays multiple images, creating a chaotic image of the city and its clashing elements.
It was a strange experience watching a completely silent film, and my friend and I filled the air with our own snark soundtrack. The movie is a little heavy-handed (because it's a silent movie you get the over-acting that was part of the form) and looks a little cheesy by modern standards, but even with that and the added sarcasm it was surprisingly affecting and very enjoyable. Which may have something to do with why it won three of the first Oscars ever given out, for Best Picture, Best Lead Actress, and Best Cinematography.
If your thing is action movies and not much else, this isn't for you. But if you have any interest in cinema history, put this at the top of your list to watch.