Along Rouen's Seine Riverfront, BIG's Sail Congress Center features a sail-like timber roof with photovoltaic panels for renewable energy and Passivhaus certification. Timber-glass facades echo local half-timbered styles, with the river side elevated on columns and the urban side forming shaded wave canopies over stone plazas with native plants. Inside, a bright foyer connects two auditoriums, exhibition halls, multipurpose rooms, and a restaurant. Prioritizing natural ventilation, modular timber, and biophilic design, it revitalizes the waterfront as a sustainable public hub.