Possibly the best line in the film.
Whilst at the Fortress of Solitude Kitty comments to Lex:-
'You act like you've been here before'.
I think this is a great line as we know that Lex HAS INDEED been there before..in Superman 2! This is a great hark back to the earlier films, it's a feel good moment for the fans. We all know what event took place there. I love this line.