The construction of the Basilica's dome in 1937 brought with it a spirit of architectural innovation on the part of Dom Paul Bellot, OSB. Rather than merely capping the building with a dome, this architect looked ahead and planned for a second, smaller dome set within the exterior dome, with the goal of facilitating the heating management for the immense nave. It is within this empty space between the two domes that the first stop on the way to the Observatory will be located.

This stage, situated at the base of the domes, will consist of a vast circular gallery (see above photo). From one side, visitors can look out on the countryside at their leisure and on the other side admire the building's interior. With an especially impressive feature, this level will offer a dizzying view straight down onto the floor of the sanctuary and the nave of the Basilica far below.

The climax of the trip to the future Observatory lies in the 18 foot diameter lantern perched atop the dome. At 243 meters above river level, it is the highest point on the island of Montreal. Eight plate glass windows surround the lantern offering a unique panorama, stretching all the way to the United States border on the South, and up to the Laurentian mountains to the north.

This plan is not a new feature in itself, for a sketch of the dome published in the Annales de Saint-Joseph du Mont-Royal magazine in January of 1938 mentioned an observation gallery as well as an Observatory deck, the present lantern. It will take a major construction project before the public can have access to this Observatory in safety. Plans and preliminary studies will be produced by the architectural firm of Jodoin Lamarrre Pratte and Associates of Montreal.