St. Peter and Paul Co-cathedral, Osijek

Osijek (Croatian pronunciation: [ôsijeːk] ) is the largest city and the economic and cultural hub of the eastern Croatian region of Slavonia, as well as the administrative seat of Osijek-Baranja County. It is the fourth-largest city in Croatia, with a population of 96,313 recorded in the 2021 census.

The Croatian National Theatre (Croatian: Hrvatsko narodno kazalište u Osijeku) is a theatre building in Osijek, capital of the Croatian region of Slavonia. Opened in 1866, and the building was expanded and fully completed in 1907 according to the plans of its local architect, Karlo Klausner.

Tvrđa (Citadel) is the old town of the city of Osijek in Croatia. It is the best-preserved and largest ensemble of Baroque buildings in Croatia and consists of a Habsburg star fort built on the right bank of the River Drava.

Museum of Slavonia (Croatian: Muzej Slavonije) is the largest general-type museum in Croatia. It is located in the Tvrđa district of Osijek.