The paper brings news about the re-discovery of the source Historia Collegii Fluminis S. Viti ab anno MDCXXVIII, a fundamental source for researching the history of the College of the Society of Jesus in Rijeka in the 17th and 18th centuries. The context of the removal of this Historia Domus (“house history”) from Rijeka after World War II is described, including how it ended up in the Jesuit archives in Italy. In 1947 Giuseppe Viezzoli alienated the manuscript from Rijeka, then under communist rule, and through his Jesuit brother Lorenzo, handed it over to the Jesuit archive in Gallarate, Italy. This action deprived the city of Rijeka of a valuable part of its archival records and cultural heritage, as the manuscript is an important source for researching local, church, and educational history. The basic characteristics of the activities of the Jesuits in Rijeka from 1627 to 1773 are presented, as well as the general characteristics of the found source. Explaining the place and role of the Historiae Domus in the activities of the Jesuits, particularly in relation to the interactions between the central structures of the Society of Jesus and the local Jesuits around the world, the paper offers insights on how historiography should approach such sources. It should be known that Historiae are an expression of the Jesuit selection of the news that the community itself felt should be remembered and are created in accordance with the instructions from the headquarters of the Order. Historia Collegii Fluminis S. Viti contains valuable data for the historical research of the early modern period in Rijeka and its surroundings, but its content should not be regarded as an entirely objective historical source, as it reflects, to some extent, a matter of selected memory.