The Donja Gradina Memorial Site is positioned in the most prominent area of the complex on the northwest side of the Kozarska Dubica plain. The area is surrounded by rivers: the Sava, the Una and an armlet of the Una called Tišina (Silence). The total area covers 808 acres, and the narrower zone is spread over 117 acres.
The Donja Gradina Memorial Site is the largest killing site of Serbian people, and it is a part of the concentration camp Jasenovac, which was formed during the time of the Independent State of Croatia (ISC) in World War II. More than 700,000 men, women, and children were murdered in torturous ways at the Jasenovac concentration camp. Most of the victims were Serbs, Jews, Roma and antifascists, no matter what their religion or nation was. Out of the total number of victims, 366,000 were killed in Donja Gradina. The Ustasha-fascist forces of Ante Pavelić committed genocide against Serbs, Jews and Roma in the Jasenovac concentration camp and the largest killing site at Donja Gradina, in order to create an ethnically pure Independent State of Croatia. The horror at Jasenovac lasted from August of 1941 until April 22, 1945.
At the end of World War II, the disposition of the Jasenovac concentration camp was unique. Concentration camps in other fascist coalition countries were turned into memorials as reminders to Mankind, but at Jasenovac, all buildings were destroyed and everything was leveled to the ground, and traces of the Ustasha crimes were removed. Not until 1965 was The Flower monument built, and the museum was opened in 1968. Since then, the area was organized as the Jasenovac Memorial Site with the Donja Gradina Memorial unit. The institution operated until the autumn of 1991 with this organization. With the disintegration of the Socialist Federal Republic of Yugoslavia (SFRY), the Jasenovac Memorial Site was separated as well. Jasenovac remained in Republic of Croatia and Donja Gradina in the Republic of Srpska, in Bosnia and Herzegovina.
The entire area of the Donja Gradina Memorial Site (117 acres) has been explored and protected. So far, 105 mass graves of enormous dimensions have been discovered. The graves are spread across nine grave fields: Tišina (Silence), Topole (Poplar), Hrastovi (Oak), Jasen (Ash), Bare (Pudles), Košute (Hinds), Brijestovi (Elms), Orlovače (Eagles) and Vrbe (Willows). The largest number of identified grave fields of victims of Ustasha crimes of genocide is in the area of Donja Gradina, but still there are locations that have not been explored and registered yet. In addition to the mass graves, there is The Poplar of Horror in Donja Gradina. Ustashas hung thousands of men, women and children on that tree, torturing them horribly before the hangings. There are also remains of the Ustasha soap factory in Donja Gradina where Ustashas made soap from body parts of the inmates.
After September 1991 and the disintegration of the SFRY and dividing of the united Jasenovac Memorial, the Donja Gradina Memorial Site lost its status, and no one was managing it in institutional terms. On July 9, 1996, the National Assembly of the Republic of Srpska passed a law regulating the status of the Donja Gradina Memorial Site in the Republic of Srpska.