Vukovar is a city in Croatia, in the eastern regions of Syrmia and Slavonia. It contains Croatia's largest river port, located at the confluence of the Vuka and the Danube. Vukovar is the seat of Vukovar-Syrmia County and the second largest city in the county after Vinkovci. The city's registered population was 22,616 in the 2021 census, with a total of 23,536 in the municipality.

Syrmia is a region of the southern Pannonian Plain, which lies between the Danube and Sava rivers. It is divided between Serbia and Croatia. Most of the region is flat, with the exception of the low Fruška gora mountain stretching along the Danube in its northern part.