After loosing his first ten million dollars to Le Chiffre, Bond is contemplating on the balcony/terrace of the Salon Privé. The exterior of the casino and the balcony were recreated in studio but were very true to the original building. Therefore you can recognize the balustrade and the pillars from the real building. The only thing that gives away this as a studio set are the terrace doors in the background.
"-Looks like I'm gonna need the other five million to buy back in..."
-Bond to Vesper-
Even the original pattern on the doors to the real building have been reused on the windows of the casino doors in the studio. In the original circle it says Louis XIV, this has been changed to CR naturally. Lamont did, as always, a splendid job with both the exterior and interior production design. Despite the fact that a large part of the second half of the film takes place in and around the casino, the exterior of the building only features a few times on screen. However, the entrance featured prominently in two of the movie posters. One of the posters features Vesper standing on the steps in front of the entrance to Casino Royale. In one of the trailers, we saw a brief glimpse of the entrance, but that scene was cut from the finished film. The only full view we get of the casino is the first time when Bond arrives to the poker game.