NSK Day is observed on 22 February, commemorating the printing of the first book in the Croatian language in 1483 – Missal According to the Law of the Roman Court, the oldest book printed in Glagolitic script. The official celebration of NSK Day and the library's 418th anniversary will take place on 21 February, featuring the presentation of NSK Awards and Recognitions.
During the Open Days, visitors will be able to tour various collections three times daily with prior registration. The Manuscripts and Old Books Collection will feature works by Croatian literary classics such as August Šenoa, Antun Gustav Matoš, Ivana Brlić-Mažuranić and others. The Map and Atlas Collection will showcase maps from the 18th and 19th centuries, including the first plan of Zagreb's Maksimir Park from 1846, a map of Ston from 1819, a plan of Zadar from 1862, a plan of Osijek from 1760, Pavao Ritter Vitezović's 1701 map of Mount Velebit, and a 1790 map of Dalmatia.
The Music and Audio Collection will present manuscripts by composers Vatroslav Lisinski, Ivan Zajc Junior, and contemporary authors Silvio Foretić and Miroslav Miletić. The Graphic Collection will display drawings, prints, posters, postcards and other artistic works from the 15th century to the present, including pieces by Menci Clement Crnčić, Ljubo Babić, Slava Raškaj, Milan Trenc and others.
Workshops and additional activities will be held in the library’s main and small foyers. At the conservation and restoration workshop, visitors will be able to try basic book repairs and hand-binding techniques, while the librarianship workshop will provide insights into collection organisation.
Attendees will also be able to participate in creating colouring books featuring NSK collection motifs and solving crossword puzzles from historical newspaper editions.