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
Cologne City Hall immediacy as a free imperial city. In 1388 Pope Urban VI signed the charter for the University of Cologne, Europe's first university to have been established by citizenry. On 14. September 1396 the constitution of Cologne came into effect and the Cologne gaffs and guilds ("Gaffeln" and "Zünfte") assumed power in the council. Following the tradition of Roman consuls, the council was headed by two elected Burgomasters (Mayors) until the year 1797, when council and constitution were replaced by the Napoleonic and later code civil. Since 1815 the city council is led by one Oberbürgermeister (Lord Mayor). During the bombing