On 13rd October 2016 the Chiostergi-Tuscher archive and library, originating from the heirs' house located in France (Saint-Cergues Les Voirons), was transferred to the Centro cooperativo mazziniano "Pensiero e Azione" in Senigallia. The paper reports about how this remarkable heritage of Chiostergi-Tuscher was retrieved and returned to Italy after thirty years. The collection includes correspondences, letters, diaries, documents, journals and papers, pictures, books, posters and other archival and bibliographic materials of great historical value to learn about the political, civic and cultural activities of Giuseppe Chiostergi (1899-1961), anti-fascist, member of the Italian Constituent Assembly and of Parliament, ambassador, pro-European and statesman, friend and correspondent to leading Italian and European personalities in the 20th century. [ABSTRACT FROM AUTHOR]