Union Station connects the TTC, Go Train, VIA train, and other transit. It connects to the Air Canada Center, the CN Tower, and the Rogers Center. The station lies right on the Path, and it is a great old historic building. I guess the downside of the building is, it's not very well planned. It's just sort of been built, and added to for so long, that it's not a very user friendly building to us. Not to mention the fact that it's not very accessible to people who have mobility issues.
The train station is decent, but it needs work.