This article investigates the Apostolic Nunciature as an administrative and political resource in the processes of knowledge production and circulation within the complex relationship between the Roman Curia, especially the Sacra Congregatio Concilii, and the local level. Focusing mainly on the Nunciature of Vienna in the second half of the 17th century and specifically on one of the great papal diplomats of this century, Francesco Buonvisi (1626–1700), who, between 1675 and 1689, held the position of an apostolic nuncio at the imperial court of Leopold I, we can explore papal representations as an indispensable tool in the procedures for obtaining and handling information. Treating the papal diplomats as actors in their own right offers a route towards a better understanding of the different and diverse processes of „diplomacy“ as well as of their duties and activities in the Apostolic Nunciature of the early modern period. The papal nuncio served at the imperial court as „connector“ between two (divergent) worlds as well as an indispensable partner to the Congregation of the Council, the Roman Curia and the pope in the administration of justice and an important mediator in the promotion and enforcement of the reform decrees of the Council of Trent on a local level. Apostolic nuncios were not merely the „objects“ of communication of the Roman Curia or of the pope. They participate actively and highly effectively in the government of the Church and in the communication between Rome, their respective court and the territories and dioceses of the orbis catholicus.