Stalker (1979)

Stalker is slow. Very slow. A guide leads two men through "the Zone", a mysterious restricted area where the normal rules of nature don't seem to apply, towards a room that supposedly grants your deepest wish. There's very little science here - the Zone is never explained, and that's deliberate. But it's hard to watch now without thinking of Chernobyl, which became a real-life exclusion zone only a few years later. It's hard work as entertainment, but it's a haunting, beautiful film, and it's stayed with me.