Since August 2021, the National and University Library has been inscribed as part of Plečnik's legacy on the UNESCO World Heritage List.

[3] In 2011, the library kept about 1,307,000 books, 8,700 manuscripts, and numerous other text, visual and multimedia resources,[4] and was (in 2010) subscribed to 7900 periodicals.

In 1919, it was named State Reference Library and started to collect legal deposit copies from the entire Slovenia of the time.

However, persistent student protests and demonstrations have been effective,[7] and the new building was erected between 1936 and 1941 by the company of the constructor Matko Curk.

In its size and form, it models the former Ducal Court (Knežji dvorec), which was at the same location and was destroyed in the 1895 earthquake.

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.

The side entrance from Gentry Street is decorated with a sculpture of Moses, created by Lojze Dolinar.

This symbolises the central thought of the building's architecture, "From the twilight of ignorance to the light of knowledge and enlightenment".

There were several causes for the delay, among them problems in the process of the acquisition of the real estate, the preparation of the documentation necessary to obtain the construction permit and the archaeological excavations of the remains of the Roman castrum Emona that took place in 1990–99 and in 2008.

[9] In 2009, the Ministry of Higher Education, Science and Technology, led by Gregor Golobič, found the original plans outdated and decided that the competition had to be repeated.