Ostberlin, or East Berlin, was the capital of the German Democratic Republic (GDR) from 1949 until the reunification of Germany in 1990. It was established after World War II when Germany was divided into East and West. The city was known for its socialist architecture, state-controlled economy, and significant historical events, including the construction of the Berlin Wall in 1961. The area was characterized by a distinct political and cultural atmosphere, with institutions like the Stasi (secret police) and various state-run organizations. After reunification, Ostberlin underwent significant changes, blending its rich history with modern developments and becoming an integral part of the unified Berlin.