A Jury Room (And That's It)
Ever since people started making movies, it's like some of them try to show off how great they are by taking an incredibly limited setting and showing what they can do inside that setting. And that's definitely the case for 12 Angry Men, which on the scale of cramped settings falls somewhere between Snakes on a Plane and Phone Booth.
One of the great things about this small setting is the way it directly contributes to the characters' sense of isolation and claustrophobia—which just makes it all that much easier for them to get frustrated and with each other. Put it all together, and you've got yourself a setting for some great drama. Kudos to director Sidney Lumet for doing such an awesome job with the small space.