Osijek is the fourth-largest city in Croatia, with a population of 96,848 in 2021. It is the largest city and the economic and cultural centre of th…Osijek is the fourth-largest city in Croatia, with a population of 96,848 in 2021. It is the largest city and the economic and cultural centre of the eastern Croatian region of Slavonia, as well as the administrative centre of Osijek-Baranja County. Osijek is on the right bank of the Drava River, 25 km upstream of its confluence with the Danube, at an elevation of 94 m.