Notre-Dame Basilica of Montreal flanks one side of Place d’Armes square. Located in the heart of Montreal’s historic district, the inside of the basilica is truly a sight to behold, and is one of the most dramatic basilica interiors in the world.  Once the largest basilica in North America, it is still often regarded as a masterpiece of Gothic Revival architecture. It’s also the oldest Catholic church in Montreal. The famous stained glass highlights the unique early history of Montreal and a tour is recommended for all ages, but may be of particular interest to older children.