During World War II it was becoming increasingly clear that Nazi terror and war were leading to a refugee crisis of enormous dimension throughout Europe. Early on it was apparent that innumerous families had been torn apart and that people all over Europe would be searching for each other. For this reason, the Allied Forces as well as the non-military organizations, such as the British Red Cross Society and the United Nations Relief and Rehabilitation Administration (UNRRA) were discussing as early as in 1942/1943 the need to search for missing people.
When the power of National Socialist Germany began crumbling in early 1943, the Allies, acting on the initiative of the Headquarters of the Allied Forces of the British Red Cross in London, changed the Department for International Affairs into a central tracing office. This office immediately began the task of tracing and registering missing persons.
One of the first endeavors of the Allies was to gather detailed information on the situation of the prisoners, forced laborers and refugees in Central Europe. This task was coordinated by the Supreme Headquarters Allied Expeditionary Forces (SHAEF), which also assumed the work of the central tracing office on 15 February 1944. The location of this office moved with the Western Allied troops, which were gradually nearing the Reich borders, and then established its temporary headquarters in occupied Germany in Frankfurt am Main.
Between 3 and 6 January 1946 the offices of the Central Tracing Service moved from Frankfurt am Main to Arolsen.
The small town of Arolsen, in northern Hesse, was chosen because of its central location between the four occupation zones and because it had large, undamaged buildings and good telephone and telegraph connections.
At first, the ITS archives were housed in an office building (today the town hall) and from 1949 until 1952 in the former SS barracks because the barracks offered sufficient infrastructure necessary for holding the huge number of documents and for accommodating the staff.
In the early 1950s, Arolsen was finally chosen as the location for the ITS which put an end to the discussions concerning the right place. In 1952, the Federal Assets Management Office (Bundesvermögensamt) had the main building in Grosse Allee erected.
Today, the ITS is housed in three other buildings in addition to the main office: the Haus am Park, the Kurhaus and a building in the Schlossstraße.