 The interiors for the hotel scene were filmed (mostly) at the famous  Biltmore Hotel in Los Angeles, on the corner of 5th and Grand. This  famous location has been used for hundreds of films, TV shows,  commercials and even a few music videos. The three doors that the  Ghostbusters walk through in the movie are actually located on the  entrance on 5th St. The Grand Avenue entrance leads you to the main  lobby, which used to be the hotel ballroom, as seen in the film.  (The ceiling is a dead give away.) The rooms formerly solid walls  have been replaced by glass doors (at the entrance) and archways.  The reception desk is where the long banquet table was located in  the film. To the right of that would have been the bar that Egon  blasts. If you go into the bar to the right of the main lobby, there  is a picture of the old ballroom on one of the walls, giving you a  better perspective of what the room looked like in the early 80s.