The Great Arch tells the true story of architect Johan Otto von Spreckelsen, whose unexpected winning design for the monumental arch in Paris's La Défense district turned him into a reluctant visionary. The film follows his journey: balancing ambitious aesthetic vision with technical, political and financial obstacles, and confronting the heavy weight of realizing a dream on a grand scale. With compelling performances and historical drama, the film delves into ambition, creation, and the human cost behind architectural icons.