The image depicts the sumptuous wedding of Francis I of Austria (later the final Holy Roman Emperor, Francis II) and Elizabeth of Württemberg in 1788. Note that the title of the image is given in both German and French, an indication of the intertwining nature of the Habsburg and Bourbon dynasties as well as the dominant position of French as a language of diplomacy in the eighteenth century.
Source: Wedding of Archduke Franz to Elisabeth Wilhelmine of Württemberg at the Burgkapelle on January 6, 1788. Engraving by Jakob (Jacob) Adam after a drawing by Johann Christian Sambach, 1788. Wien Museum Inv.-Nr. 220106, CC0 (https://sammlung.wienmuseum.at/objekt/5326/)
Wien Museum