This 19th-century stained glass window in the Church of Saint-Godard (Église Saint-Godard), Rouen, Normandy, France, commemorates Pope Pius IX's solemn declaration of the dogma of the Immaculate Conception of the Virgin Mary ⓘ on December 8, 1854, in the papal bull Ineffabilis Deus. This event, defining Mary's preservation from original sin at her conception as revealed doctrine, was a pivotal moment in 19th-century Catholic Mariology, celebrated amid the Gothic Revival and Ultramontane movements emphasizing papal authority. The window, likely installed in the 1860s as part of the post-Revolutionary restorations, reflects Rouen's rich stained glass tradition and the city's role as a center for Marian devotion during the period.