McCabe & Mrs. Miller

I couldn't find the exact scene, but my favorite moment of this film is also one of my favorite moments in film. McCabe enters Mrs.Miller's room & the two begin a discussion. (Some backstory: Miller runs the brothel in the small remote town the two of them run.) The neighboring room is occupied by one of her girls and a workman. The prostitute and the customer completely forget about sex, instead the two of them stand together giggling & peeping on Miller & McCabe, who are their bosses pretty much. There are allot of memorable moments in the film, it has a unique look, & fictively depicts a moment in Pacific Northwest history.
The first Star Wars

Biggest moment of my childhood.
Swan Lake, 1981 anime

Another memorable opening. The first anime I ever saw, & probably the first version of Swan Lake I knew. I am angry that I can't find it (legally) anymore.
There are plenty more that are important to me, but I think these three are the most personally significant.
The Battle of Algiers has to be one of the strangest most depressing films I've ever seen. I am in wonder of it. I think it's amazing how many of the people who were involved IRL they were able to bring into the film. And that bombing scene was tragic and incredible. I don't have any connection to either side in that story, but I could not relate to anyone in that film. I don't understand the reasoning behind the violence, and it made me feel against them which is strange because they helped tell the story. That seemed antithetical to the whole victors write history thing, & I can't believe they'd tell a story that would make me see them as wrong. It's a testament.