Examples of movie magic that still blow your mind?

I have create feature fever and I've been checking out a lot of monster movies, some recent, some classic, but then I got to revisit King Kong 1933 and honestly the stuff these guys were able to do in the 30s is insane, especially with the technology they had at the time.

Not just the King Kong but the rear projection and stop motion with the animals on the island in general is just crazy, especially with how a lot of them interact with the people but King Kong himself is just a incredible feat with so much work from mixing miniatures, stop motion and creating giant models it's crazy to think about.