I finally got round to watching Metropolis (1927) after years of meaning to. It's is frankly incredible both visually, technically and in terms of narrative. The original sci-fi blockbuster. In a way it shows how small a distance the genre has traveled, or maybe how far ahead of it's time it was.
Here's a link to the (almost) full restored version which was thought lost until a copy was found in an Argentinian museum in 2008.