This is a fun little museum. It starts with a 15-minute or so video on the history of Montreal, where everyone gets headphones and can select one of eight languages and control their volume. This museum is on one of the oldest sites in town and there are ruins from some of the old buildings that used to stand there. One such ruin is right in the theater and they talk about it in the movie.
One of the exhibits is an old former sewer line that now serves as a tunnel. It is lit up and has some epcot-y music. Very cool.