Terezín is a town in Litoměřice District in the Ústí nad Labem Region of the Czech Republic. It has about 2,900 inhabitants. Founded in 1780, Terezín is a former military fortress composed of the citadel and adjacent walled garrison town. The town centre is well preserved and is protected as an urban monument reservation. Terezín is infamously known as the location of the Nazis' Theresienstadt Ghetto.

During the second half of the 19th century, the fortress was also used as a prison. During World War I, the fortress was used as a political prison camp. Soldiers and civilians who showed opposition to the war were imprisoned here.

After the Munich Agreement in September 1938 and following the occupation of the rest of Czechoslovakia in March 1939, with the existing prisons gradually filled up as a result of the Nazi terror, the Prague Gestapo Police prison was set up in the Small Fortress in 1940. The first inmates arrived on 14 June 1940. By the end of the war 32,000 prisoners of whom 5,000 were women passed through the Small Fortress. These were primarily Czechs, later other nationals, for instance citizens of the former Soviet Union, Poles, Germans, and Yugoslavs. Most of the prisoners were arrested for various acts of resistance to the Nazi regime; among them were the family members and supporters of the assassins of Reinhard Heydrich.

By 1940, Germany assigned the Gestapo to adapt Terezín, better known by the German name Theresienstadt, as a ghetto and concentration camp. Considerable work was done in the next two years to adapt the complex for the dense overcrowding that inmates would be subjected to. It held primarily Jews from Czechoslovakia, as well as tens of thousands of Jews deported chiefly from Germany and Austria, as well as hundreds from the Netherlands and Denmark. More than 150,000 Jews were sent there, including 15,000 children.[8][9]

Although it was not an extermination camp, about 33,000 died in the ghetto. This was mostly due to the appalling conditions arising out of extreme population density, malnutrition and disease. About 88,000 inhabitants were deported to Auschwitz and the other extermination camps. As late as the end of 1944, the Germans were still deporting Jews to the death camps. At the end of the war, there were 17,247 survivors of Theresienstadt (including some who had survived the death camps).