A series of service spaces extends alongside the monumental entrance staircase. On the left, beyond the central hall, visitors first encounter the Technical Office and then the Director's Office, connected by an antechamber. On the opposite side are the photocopying room and an intermediate hallway leading to what once served as the Assistant Librarian's Office and now functions as the Information Desk.

Today these spaces appear relatively understated. Their walls are finished in plain plaster and display no immediately visible decoration. Recent investigations, however, have uncovered evidence of a far more elaborate past. Most notably, beneath the modern finishes of the current Information Desk, traces of earlier decorative schemes have been revealed. These remains are concentrated mainly along the upper sections of the walls near the ceiling, following a continuous horizontal pattern around the entire room.

They are most likely tempera paintings on plaster, executed with natural pigments applied in thin glazes. Despite the passage of time and their fragile state of preservation, decorative motifs remain visible, including painted architectural frames, small friezes and delicate stylised vegetal ornament. Although faint, the designs suggest a restrained decorative style combining Neoclassical and Eclectic influences, dating from the late 19th or early 20th century.

The decoration also reveals a sophisticated use of chiaroscuro, employed to create an illusion of depth and to enrich otherwise flat surfaces. Although altered over time, the colours still reveal soft shades of ash grey, ochre, pinkish beige and hints of green. The light ivory-toned background originally enhanced the diffusion of natural light and brightened the room.

The presence of such decoration on both the walls and the ceiling suggests that this space once played a more prestigious role than it does today. It was likely intended as a space of considerable importance, serving administrative or reception functions.