The initial phase of the decoration planned by the architect, O'Donnell attracted much criticism. In fact, the decor during the early years, shows developments that are rather different to ones at present.

The wall of the sanctuary, which was very flat as the tradition of the English Gothic churches dictated, presented a large canopy. This canopy blinded the congregation by causing a back-lit effect...

La Fabrique, under the direction of the parish priest, Victor Rousselot, then decided to redevelop the interior and involved Montreal architect, Victor Bourgeau, in this project.

From 1870 to 1900, Rousselot and Bourgeau worked on a style and symbolism inspired by the Sainte-Chapelle in Paris. It is the colours selected, the motifs of the gold leaves in the vault and the columns that especially remind us of the Sainte-Chapelle.

Blue, gold leaves and the columns are what makes the Basilica so breathtaking.

You will find six paintings in the décor, from the old church (see image below).

Some paintings of the first church are now in the Basilica.

To cut down on costs, the main altar of the old church was placed in the sanctuary; today this altar can be found in the lateral chapel dedicated to Saint Margaret of Youville.