This representative building was built in 1900 for the needs of the Montenegrin royal court. The vision of King Nicholas I of Montenegro was to provide Nikšić with several representative buildings: Cathedral church, court, large parks and so-called Trebjesa Reserve. The castel was built in neo-renaissance style and was designed by a Croatian engineer Josip Slade and is one of the most valuable curtural heritage in Montenegro. Entrance facade is characterised by colonnades on both floors. Beneath the ground colonnade there once was, in its original form, a covered entrance porch, which was glazed later on. Facade features numerous windows with arched ends and emphasised frames, set i n a regular sequence. From 1919 until the Second World War the complex served as a grammar school. During the Second World War the castel was significantly damaged and from 1949 to 1975 its housed and elementary school. Today, it is the place of Nikšić Heritage Museum, City Library, Gallery and Archive. Particulary valuable is Museum Archaeological collection originating from Crvena stijena ( Red rock), which is a famous archaeological site. Furthermore, there are collections related to ancient time, the Middle Ages and liberation wars. Within the museum complex there is an ethnological collection. The castel of Nicolas I of Montenegro, together with Cathedral Church of St. Basil of Ostrog, is one of the most significant elements of Nikšić urban style and identity.