After the enormous success of Le nozze di Figaro at Prague's Nostitz Theater in 1786 and the world premiere of Don Giovanni there in 1787, Mozart's operas became canonic works in the Bohemian capital, with numerous performances every season throughout the nineteenth century. These nineteenth-century Prague Mozart productions are particularly well documented in the previously overlooked collection of theater posters from the Czech National Museum and the mid-nineteenth-century manuscript scores of Le nozze di Figaro . Much sooner than elsewhere in Europe, Prague's critics, audiences, and opera institutions aimed at historically informed, “authentic” productions of these operas. This article shows that the attempts to transform Mozart's operas into autonomous artworks, artworks that would faithfully reflect the unique vision of their creator and not succumb to changing audience tastes, were closely linked to national politics in nineteenth-century Prague. As the city's population became more and more divided into ethnic Czechs and Germans, both groups appropriated Mozart for their own narratives of cultural uniqueness and cultivation. The attempts at historic authenticity originated already in the 1820s, when Czech opera performers and critics wanted to perform Don Giovanni in a form that was as close as possible to that created by Mozart in 1787 but distorted in various German singspiel adaptations. Similar attempts at historical authenticity are also prominent in Bedřich Smetana's approach to Le nozze di Figaro, during his tenure as the music director of the Czech Provisional Theater in the late 1860s. German-speaking performers and critics used claims of historical authenticity in the 1830s and 40s to stress Prague's importance as a prominent center of German culture. During the celebrations of the 1887 Don Giovanni centennial, furthermore, both the Czech and German communities in Prague appropriated Mozart's operas into their intensely nationalistic debates.