The Whitney Museum has proposed expanding in the past, but the timing (or building design) hasn’t seemed right. “Now the Whitney is trying a gentler approach. A new design by the Italian architect Renzo Piano, approved last week by the museum’s board, is conceived as a stoical nine-story tower that would rise alongside the existing 1966 landmark. The tower’s simple form and silvery copper-and-aluminum-alloy skin would be a dignified counterpoint to Marcel Breuer’s brutal dark granite masterpiece.”