History of Cologne was considered a substitute for the German University of Strasbourg, which became part of France along with the rest of Alsace. Cologne prospered during the Weimar Republic and progress was made especially in governance, city planning and social affairs. Social housing projects were considered exemplary and were copied by other German cities. As Cologne competed to host the Olympics, a modern sports stadium was erected at Müngersdorf. Beginning of the 1920s civil aviation was permitted once more, and Cologne Butzweilerhof Airport soon became a hub for national and international air traffic, second in Germany only to Berlin Tempelhof Airport. At
Transport in Cologne German limited access highway ("autobahn") was opened in 1932 between Cologne and Bonn. Today, this is A 555. In 1965 Cologne became the first German city to be fully encircled by a beltway. Shortly after the Second World War reconstruction plans by, among others, Rudolf Schwarz called for a downtown bypass freeway (the ) as a centerpiece of rebuilding the city. These schemes were only partially executed though, due to opposition by environmental groups. The completed section became "Bundesstraße (Federal Road) B 55a" which begins at the "Zoobrücke (Zoo Bridge)" and meets with A 4 and A 3 autobahns at