2001: A Space Odyssey
Haven’t seen this since I was a child. What really struck me about it is how little happens in it, despite that is a 2.5 hour movie. World building is done with excruciating finesse and detail. Minutes go by without a single word being uttered, without any advancement of the story beyond the initial frames of the scene.
Yet one is never bored. Every frame is visually stunning. One is constantly engaged. The ending is an incredibly emotional experience, despite the fact one has no idea what is going on.
A true masterpiece.