It was used for "Tollana", the second homeworld of the Tollans. Ever since learning that I've wanted to put a giant Nerf gun dressed up as one of the Tollan Ion Cannons on campus };>.

Another location that gets a fair bit of use is Toronto City Hall (low saucer-shaped building with two semi-cylindrical skyscrapers wrapped around it). The first time I saw it being used was as one of the destinations shown through an alien portal. The most recent one I've heard about was as Umbrella Corporation headquarters in Resident Evil (people in the theatre reportedly cheered when it was blown up).

I'm sure there are many more locations that show up repeatedly that I'm not recognizing.