Flossenbürg, Nazi German concentration camp, established in 1937 in the market town of Flossenbürg, near the Czech border in Bavaria, Germany. It was originally used for political prisoners but, by World War II, had become an important forced-labor center, housing 30,000 to 40,000 worker-prisoners in the main camp and 15 satellite camps. From 1942 on, it was also a transit camp for Jews destined for the extermination camps in German-occupied Poland.