A trip to Montreal just isn't complete without a visit to the Notre Dame Basilica. I was shocked that there's a line to go inside this church! The $5 admissions fee is fair in order to maintain and support the building. It comes with a free tour but there were only 2 English tours offered that Sunday afternoon and we came right in the middle between those two time slots.
The interior is breathtaking with all the different colors coming from the stained glass windows, candle holders, and lights. A lot of tourists sit on the benches just to soak in the atmosphere (and air conditioning on a hot day). It's very peaceful despite the crowd. I was relieved to see that there is a functional prayer room near the exit on your left for non-touristy purposes.
Don't forget to check out the chapel in the back. It's quite different but still mesmerizing.