He took a new direction at the end of the 1950s as one of the first Quebec artists who saw the necessity of integrating art into the urban environment. His most important contributions are thus original murals and other collaborations with architects.
Jean-Paul Mousseau did a great deal of important work in the Montreal metro. He clashed with the metro's first art director, Robert Lapalme, who insisted that metro art be figurative, represent Montreal history, and be sponsored. Mousseau wished to open the doors to non-figurative art integrated into the architecture and accounted for in the construction budget. Lapalme held sway over the initial network, except for two works (Mousseau's circles at Peel station and Marcelle Ferron's stained glass at Champ-de-Mars) which he always regretted.
Mousseau took over as art director after LaPalme, and his influence marked all the rest of the network, which includes stunning works of non-figurative art integrated with the architecture. Most of the artwork was planned in accordance with the architects, and many were by the architects themselves. Other works by Mousseau in the metro include the mural Opus 74 at Viau station, two murals at Honoré-Beaugrand, and a mural (temporarily removed) at Square-Victoria.
His work is also integral to Montreal's airport and several of its skyscrapers. A major work is a mural (Lumière et mouvement) in the Hydro-Québec building in Montreal.
See List of Quebecois.