question of the weekend: what is your seminal movie?

A tweet this week reminded me exactly when I feel hopelessly in love with movies:

I was 12 years old, and I was irretrievably hooked by movie magic. I have earlier memories of exciting movies, but Raiders of the Lost Ark is the movie that cemented my adoration.

Your turn:

What is your seminal movie? Define “seminal” however you like. Or perhaps you have a seminal movie experience or movie moment, not a film itself but a moviegoing experience or an association that made you fall in love with cinema.

(You can also discuss this at FlickFilosopher.com, if you prefer.)