Citizen Kane
I got to watch this for the first time in theaters for the 85th anniversary and I was very pleasantly surprised. I know this is one of the most praised movies of all time and it is definitely for good reason. I unfortunately missed the first 13 minutes or so in theaters so I was missing some context throughout. Missing that opening is a huge regret of mine for sure, but watching it after the fact was still great. Overall, a must-watch for film fans.