The expansion of Bibliothèque L'Octogone offers a contemporary reinterpretation of one of LaSalle’s landmark buildings, where architecture becomes at once a vessel of memory, an urban landmark, and a catalyst for socio-ecological transition. Located at a strategic crossroads, the library has been redefined as a major cultural and social hub for the community, a vibrant and welcoming place for sharing, creating, and learning that responds to the evolving needs of a growing and changing population. The project is the culmination of years of needs assessments, public consultations, and an architectural competition aimed at transforming an existing facility into an inclusive, luminous, and open civic destination.

Rather than erasing the building’s distinctive character, the project places it at the heart of the design concept. The original octagonal volume is preserved, revealed, and extended through the addition of a new floor, increasing the library’s area from 2,645 m² to nearly 4,500 m². This intervention transforms an originally introverted form into a distinctive architectural gesture while limiting the building footprint and maximizing the reuse of the existing structure. In doing so, it avoids up to 261,000 kg of CO₂ emissions and diverts 870 m³ of construction waste from disposal.

Drawing inspiration from LaSalle’s history, from the Lachine Canal to the Fleming Windmill, the architecture is organized around a fluid and ascending spatial progression. From Dollard Avenue, a generous public area leads visitors into a large hall, a central interior node that connects the city to the park. This central gathering space orients visitors and structures circulation toward the library’s various program areas, as well as the rooftop terraces and gardens.

Three lanterns define both the building and its uses. The Urban Lantern is situated above the administrative and support areas of the existing library, establishing a distinctive landmark at the northeast corner of Dollard Avenue and Salley Street. Animated by workspaces framed within comic-strip-inspired openings, its transparent façade opens toward the exterior public space.

To the southwest, the Pastoral Lantern extends toward Félix-Leclerc Park and the Aqueduct Canal, drawing its structural rhythm from the large octagonal volume below. A generous frame extends from the architectural volumetry, offering bright reading spaces and a spacious outdoor terrace.

The Community Lantern, located to the southeast, houses public spaces that benefit from a direct connection to the entrance hub and outdoor activities. In constant dialogue with the changing seasons, the café, news lounge, and Fab Lab animate a vibrant community life unfolding near the southern entrance, across adjacent terraces and lounges, and throughout the redesigned urban park surrounding the building.

Together, these three lanterns affirm the library’s role as a unifying civic place, a threshold between city and nature.

The comic book collection, a defining feature of Bibliothèque L'Octogone, runs through the architectural experience. The geometry of the spaces, custom furnishings, wayfinding elements, and sculptural staircase evoke the language of graphic storytelling, transforming the visitor journey into an immersive and playful experience.

Architectural quality is central to the user experience, with abundant natural light and interior belvederes offering views across the library and toward the sky. Art plays a prominent role in the building’s renewed identity, notably through a living wall inspired by The Great Wave off Kanagawa and a helical staircase showcasing En circulation, a suspended artwork by artist Karilee Fuglem that guides visitors toward the contemplative space known as Dans ma bulle.

From an environmental perspective, the project prioritizes the reuse of existing components, including the concrete slab and portions of the structural framework, significantly reducing carbon emissions and construction waste. Currently pursuing LEED Gold certification, the library combines a high-performance envelope, passive design strategies, energy recovery systems, and efficient mechanical systems, resulting in an energy reduction of more than 30%.