The Libraria is the former library hall of Collegium Maius which was constructed in 1516-1540. The decorative gilded Golden Portal (Porta Aurea) leads to the interior currently used as museum exhibition space. A distinctive element of the interior is the late-Gothic net vault.

Neo-Baroque cabinets contain books from the Pusłowski family collection (18-19th c.) and historic library catalogue boxes.

The busts displayed in the library depict people of culture from antiquity to the 19th century. The walls are decorated with portraits of personages who made essential contributions to the development of the Jagiellonian Library and the Jagiellonian University Museum, including the portrayals of Benedykt of Koźmin (16th c.), Józef Łepkowski (19th c.), and Karol Estreicher junior (20th c.).

Of particular note is the set of three reconstructed wooden astronomical instruments identical to those used by Nicholas Copernicus (quadrant, triquetrum and armillary sphere), as well as a 19th-century reading wheel.

The Libraria is the place for monthly sessions of the Jagiellonian University Senate.