Wow. Just an amazing piece of religious architecture. The Notre Dame Basilica is a must see when in Montreal.
Be sure to make advance reservations for the guided tour as it's excellent, and you get to see parts of the church that others don't have access to.
Standing in front of the altar and looking up at the soaring artwork and statues behind it are breathtaking.
The stained glass, the statues all around, the artwork everywhere, the different rooms to explore, the woodwork carvings, the flickering candles, the chapel, the grandiose organ and more are all just magnificent. So much to see and you can take as long as you wish. Walk around. Sit in a pew and reflect. It's a beautiful structure.
Located in the Old Town area it makes for a great day to tour the Basilica the head out for some lunch.
I took a ton of pictures but they really don't showcase the majesty of this structure. It has to be seen in person.