Many called Vienna not just the capital of the Austro-Hungarian Monarchy, but also the most beautiful city of it. Comments are invited on the topic.
I object. Vienna is always called "Wien an der blauen Donau" (as a famous song says) (i.e. Vienna is located on the blue Danube...a river that is only blue if there is no high water and the sky is blue) but, worse, the old part of Vienna was quite a distance from the Danube. Only a canal visible in the picture allows access to the real Danube for small tourist boats, that go downriver to its smaller sitter- city Bratislava and to Budapest. And it is exactly Budapest that I consider more beautiful: There the Danube is really part of the city, skirting impressive Gellert Hill, with huge historic thermal bath houses at the foot of the hill.
Bratislava, Old City Hall
All of above is only half true. There were three cities in the Austro-Hungarian Monarchy competing for the title most beautiful city: the third one is Prague, with its famous Wenzel cathedral surrounded by age-old workshops in the city center, an artistic bridge crossing the river Moldava, with old houses on both banks of the river, giving an experience hardly to be found anywhere else.
See the link
Prague by night
Well, both of you may have some good arguments, but you seem to be overlooking that all three cities have some outstanding beautiful places, but only one, VIENNA, has dozens of them.
Wien - UNO City