ENThe Manuscript Department of the Vilnius University Library contains the documents of the Vilnius Public Library, the Vilnius Museum of Antiquities and other institutions that operated between 1855 and 1915 in the facilities of todays Vilnius University. These documents form the following collections: Inventories (f. 4), Mixed (f. 5), Academia et universitas Vilnensis (1579-1773) (f. 13), Land plans (f. 23), Vilnius Public Library and Museum of Antiquities (f. 46), Autographs (f. 48), Architectural plans and drawings (f. 78), Photographs (f. 82) and others. The largest number of items is in the collection of the Vilnius Public Library and the Museum of Antiquities (f. 46). It consists of 262 documents that reflect the establishment and activities of these institutions in the period from 1852 to 1915. The current article focuses on the most important collections of f. 4 and presents the Archive of Count Eustachy Tyszkiewicz (1814-1873) as its part. The content of the archival documents is briefly reviewed and the question when, why and by whom the archive was given the name of Count Tyszkiewicz is discussed. [From the publication]