In the 1920s and '30s, it was one of the busiest traffic centers in all of Europe. Its heyday was in the 1920s, when together with the Alexanderplatz it was at the heart of Berlin's nightlife. (See 1920s Berlin)
As was the case in much of Berlin, many of the buildings around Potsdamer Platz were turned to rubble by air raids and heavy artillery bombardment during the last years of World War II. When the city was divided into sectors by the occupying Allies at the end of the war, the square found itself on the boundary between the American, British, and Soviet sectors.
As Cold War tensions rose during the Fifties, restrictions were placed on travel between the Soviet sector (East Berlin) and the western sectors (West Berlin). Lying on this invisible frontier, Potsdamer Platz was no longer an important destination for Berliners. With the construction of the Berlin Wall on August 13, 1961 along this intracity frontier, Potsdamer Platz found itself divided in two. What had once been a busy intersection had become desolate.