city in Brandenburg, capital of Germany, traditionally by folk-etymology from German Bär "bear," but likely from a Slavic source, compare Old Polabian berl-, birl- "swamp," in reference to the old city's location on low, marshy ground along the River Spree. A flashpoint city in the Cold War, the Berlin airlift ran from June 28, 1948 to May 12, 1949. The Berlin Wall began to be built Aug. 15, 1961, and was effective until Nov. 9, 1989.