Gradiška is a town and municipality in northwestern Republika Srpska, Bosnia and Herzegovina. Before the Bosnian War, it was also known as Bosanska Gradiška. Gradiška is situated in the northern part of the Bosnia and Herzegovina and is one of the eastern most municipalities of the Bosanska Krajina region. The town is situated on the Lijevče plain, at the right bank of the Sava river across Stara Gradiška, Croatia, and about 40 km (25 mi) north of Banja Luka.
According to the written documents, Gradiška was first mentioned a little more than 700 years ago under the name of Gradiški Brod. However, the life in the area of the present town, its immediate and wider environs, dates back to the prehistoric times. In the time of Roman Empire, the city named Serbinum (Servitium) existed at this location. Gradiška was mentioned as a free town. In the Middle Ages, Gradiška had a major importance as the place where the Sava river used to be crossed.