Collegium Maius, located on the corner of Św. Anny and Jagiellońska Street, is the oldest university building in Poland.
In 1400 King Ladislaus II Jagiello bequeathed a town house to the University, purchased from the town councillor Piotr Gerhardsdorf (Gersdorf). Its remaining traces are the pieces of cobblestone wall in the current building's foundations and on its corner (both on Jagiellońska Street and in the courtyard). The size of the house was insufficient for the proper functioning of the rapidly expanding university. Over the 15th century the college area was increased through the purchase of adjacent houses and the construction of new buildings. After two fires in 1462 and 1492, all the individual houses were joined as one, forming an arcade courtyard surrounded by galleries with the diamond vaults typical for the Late Gothic style. The uniform arcades were interspersed by the "Professor" staircase leading to the first floor balcony. The ground floor housed lectoria, or lecture rooms. Those long rooms with low ceilings were poorly lit and often damp. The library (libraria), the Common Room (Stuba Communis), the treasury and the theologians lecture room (the present-day Aula – assembly hall) were situated on the first floors. The dwellings of professors, or residences, were located on the first and second floors. Up to the mid-19th century the College's appearance and internal layout had not altered in a significant way. Its appearance and function completely changed with the alteration works for the period 1840-1870 giving Collegium Maius a new-Gothic look and creating a new seat for the Jagiellonian Library.
After the Library abandoned the College in 1940, it was possible for Prof. Karol Estreicher to initiate new, extensive renovation works for the period 1949-1964, including the removal of the new-Gothic additions. During this period it was decided that the building was to become the location for the Jagiellonian University Museum, giving shelter to the old University collections (works of art and keepsakes), as well as significant number of scientific instruments.