Cologne is an ancient city established by the Romans in the 1st Century AD on the banks of the Rhine and is Germany's 4th largest city with over 1 million inhabitants. Although mostly destroyed by bombing in World War II, it has been re-built resulting in a unique cityscape. It is famous for its cathedral, on which construction began in 1248 and is still in progress. Cologne has more than 30 museums and numerous art galleries. It is an important media centre with several TV and radio broadcasters based there. Adenauer, the first post-war German chancellor was mayor of Cologne. Cologne is also famous for its carnival season beginning in November and closing with a long weekend street festival in the spring.