To the left of a majestic lobby, overlooked by a mezzanine with a neoclassic-style marble balustrade, in the Gaston-Miron building, is the former office of the conservator in which is situated the Baroque-style fresco by Hector Végiard that adorns the entire ceiling. The fresco, in the image of nineteenth-century neoihistorical interiors, was restored in 1992. The walls, however, have been repainted.

Painted in oils on a thin layer of plaster, the fresco is divided into three sections. The central part illustrates an allegory for music, as personified by a bare-breasted woman holding her attribute – a lyre, the instrument of the ancient gods – in one hand; the other hand points to another instrument resting on a score, laurel leaves, and a trumpet. Her divine nature is evoked by her nudity and the Baroque draped fabric fluttering at her side, propelled by an invisible force. Several putti are scattered around the work: one notates a melody with a quill, another plays a flute, and a third plays a tambourine. Four medallions portraying historical figures surround the scene.

Two caissons frame the main scene. In the centre of the first is an allegorical motif composed of piled books, an inkwell and a quill, and a candlestick and an hourglass. The ensemble is surrounded with laurel branches, a symbol of virtue. In the centre of the caisson at the back of the piece is a group of musical instruments and a score sitting atop laurel branches.

The painting as a whole is enhanced with interlacing and motifs inspired by the Renaissance. Around the caissons is a border of modillions, dentils, and ova surmounting a broad frieze of foliage scrolls. In the four corners of the ceiling are the signatures of Hector Végiard and three other artists, E. Végiard, J. H. Houde, and Napoléon Fournier.

When he went to work as a conservator for the Municipal Library in 1930, Félix Desrochers hired Hector Végiard to paint a fresco on the ceiling and walls of his office. At the time, Végiard was 60 years old.