Stara Gradiška is a village and a municipality in the Brod-Posavina county of Croatia. It has 542 residents, while the municipality has 1,717 (2001), in six other smaller villages. It is located on the left bank of the river Sava, across Bosanska Gradiška in Bosnia and Herzegovina. The first word in the name means Old, and there's also a New Gradiška nearby, the city of Nova Gradiška. A prison was first established at Stara Gradiška in the 1920s. During World War II, the Ustaša regime used it as the Stara Gradiška concentration camp, a part of the Jasenovac complex. From 1945 until the late 1980s the prison at Stara Gradiška held political prisoners of the communist regime. In 1991 the prison was officially shut down by the democratic Republic of Croatia. The municipality plans to turn the site into a museum.
I think that Ustasa death camps like Stara Gradiska were among the cruelest death camps during WW2. Even SS officers were shocked about how victims were killed there. Ustasa didn't have gas chambers like Nazis but they killed their victims with hammers, axes, knifes, had special knife for cutting throats, buried people alive. Prisoners and victims were Serbs, Jews, Roma people, partisans, communists and other for Ustasa inferior races. In my opinion Ustasa cruelty exceeded Nazis cruelty against prisoners and can compare to Japanese cruelty against Chinese and others during WW2.