The west and north wings were finished in 1861 and 1925, respectively, after involving multiple architects, including Alexander Francis Dunlop and Harold Lea Fetherstonhaugh.

This plan ultimately took a lot longer to achieve than expected, as the Royal Institution for the Advancement of Learning did not have trustees or a board and thus could not execute the provisions of the will.

In 1839, the competition was won by John Ostell, a British architect known for designing the Old Custom House (1836) in Montreal, and soon after, construction began on the McGill College Building.

At that time, the central block contained the kitchen, steward's residence, a room for the Governors' council, college hall, library and classrooms.

Due to the building not being properly finished, the roof leaked, the rooms were cold and dark, there were rats roaming the halls and several windows were broken.

In 1852, the city began construction of the McTavish reservoir and, in the process, inadvertently ended up sending large boulders into the roof of the McGill College Building.

Hopkins to add the portico with Doric columns that the Royal Institution had previously intended to build in front of the central block, although made out of wood rather than stone.

Behind the central block, Moyse Hall was added, containing a large lecture theatre with bas-reliefs and ten electric chandeliers made of bronze.

[4] The McCall MacBain Arts Building uses a mix of Classical architectural elements, such as a front portico with a pediment held up by Tuscan columns.

[11] The wooden cupola atop the central block, from which the McGill flag flies, can be seen from the Roddick Gates and is a recognizable symbol of the university.