effort. In 1939 and 1940, the Germans carried out mass arrests of Polish intelligentsia, especially teachers, for which a prison was operated in the city (see Intelligenzaktion). Local Polish teachers were among Poles murdered in 1939 in Chorzów and Strzybnica (present-day district of Tarnowskie Góry), and later in the Dachau concentration camp. There were several forced labour camps in Chorzów, including one Polenlager solely for Poles, two camps solely for Jews, the E246, E594 and E725 subcamps of the Stalag VIII-B/344 prisoner-of-war camp, and, in years 1944–1945, a subcamp of the Auschwitz concentration camp, in which approximately 200 Jews from German-occupied France, Belgium and Czechoslovakia were imprisoned. In January 1945, the prisoners of the subcamp of Auschwitz were evacuated on foot to Gliwice, and then deported to the Nordhausen-Dora concentration camp. Chorzów was occupied by the Soviet Red Army in January 1945 with the subsequent persecution of many ethnic Polish Silesians and Germans. After 1945 At the end of World War II, Chorzów was given to Poland. Generally, the Chorzów industry suffered little damage during World War II due to its inaccessibility to Allied bombing, a Soviet Army enveloping manoeuvre in January 1945, and perhaps Albert Speer's slowness or refusal to implement the scorched earth policy. This intact industry now played a critical role in the post-war reconstruction and industrialization of Poland. After the war, businesses were nationalized and operated, with minor changes, until 1989. Some were used as Soviet labour and concentration camps. Some industrial hardware and at least 100,000 Polish Silesians were deported to the Ukrainian Donbass region. At the "fall of communism" in 1989, the area was in decline. Since 1989, the region has been transitioning from heavy industry to a more diverse economy. On 28 January 2006, a roof collapsed at an exhibition hall, killing 65 people. See Trade hall roof collapse in Katowice, Poland. In 2007, Chorzów became a part of the Upper Silesian Metropolitan Union, a voluntary union of a continuous chain of cities aimed at increasing the poor visibility of the area, improving its competitiveness, and modernizing the infrastructure. The region experienced several waves of migrations, including those commencing in 1945 (to Germany and from Poland and Ukraine), in 1971–1976 (to Germany), in 1982 (to Western countries), and from 2003 (to other countries of the EU). Geography Location Chorzów is in the middle of the largest urban center in Poland. The recently (2007)