Since 1791, the library was located in the building of
Ljubljana lyceum. In 1919, additional space was provisionally dedicated to it in the building of the
Poljane Grammar School. In 1930–31, plans for a new building were created by
Jože Plečnik. Initially the project encountered resistance by the
Yugoslavian authorities based in Belgrade. However, persistent student protests and demonstrations have been effective, and the new building was erected between 1936 and 1941 by the company of the constructor
Matko Curk. The library building is the most monumental of Plečnik's works in Slovenia. In its size and form, it models the former
Ducal Court (), which was at the same location and was destroyed in the
1895 earthquake. The building has a square ground plan and is a massive block with a court. The front façade, oriented toward Auersperg Street, was designed as a combination of brick and stone embeddings, some of them archaeological remains from the place. It was modelled in the manner of the Italian
palazzo, similar to the house of the Italian architect
Federico Zuccari. The handles of the main door end with a little head of
Pegasus. The symbiosis of the fragile glass and massive walls in other parts of exterior is entirely original. The side walls are oriented towards Gentry Street and Vega Street. The side entrance from Gentry Street is decorated with a sculpture of
Moses, created by
Lojze Dolinar. The interior comprises four wings and the central hallway. Light comes to the main entrance through windows in the main reading room, which is at the top of the main staircase, oriented crosswise. This symbolises the central thought of the building's architecture, "From the twilight of ignorance to the light of knowledge and enlightenment". The staircase and its 32 columns are built of the dark
Podpeč marble, actually
limestone. In addition, there is a small staircase with landings in the form of balconies in each of the four corner of the building. The main reading room, modelled after the industrial aesthetics of the 19th century, is decorated with large chandeliers. It has two glass walls at each side, divided in two symmetric parts by a column and forming part of the side walls of the building. There are wooden tables and chairs. The equipment in main spaces of the building is scarce. The cellar was renovated in 2000 by
Marko Mušič, when the building was also additionally protected against earthquakes. The library was depicted on the reverse of the 500
tolar banknote, issued in 1992 by the
Bank of Slovenia. ==Expansion==