My friend and I were adventurous and took the Metro subway and city bus to get to this site. It was fun and easy.
The bus let us off on the street at the bottom of the cathedral. There are MANY steps up to the cathedral. The Montreal tourist information center told us there was a shuttle one could take up to the cathedral. My friend walked up. I took the shuttle. The shuttle lets you off at the main entrance off to the back side. The cathedral does not charge to walk through. A beautiful structure.
There is a very nice gift shop with many souvenirs and religious items (statutes, rosaries, pictures, etc)
We walked around the cathedral. Nice view from the top.