Warsaw was devastated after the WWII. It is estimated that about 85% of the buildings were destroyed, and only about one thousand people lived in the ruins, compared to more than one million before the war. The communist government that was installed by the Soviet Union after the war initially decided to build a new capital city, because it was calculated that it would be cheaper to build a new one than reconstruct the old one. Later, people started to move back, and Warsaw was reconstructed instead.
Similarly, Nuremberg was something like 95% destroyed. It's strange to see it. The vast majority of the city looks obviously new, and it's all a very similar architectural style. The bricks are a little too clean, a little too straight, on these buildings designed to look 300-500 years old, that are only 30 to 60 years old--at the most!
Last Fall I was in Minsk, Belarus. I was wondering why streets are so wide. It turned out that all (for all practical purposes) buildings were destroyed by Nazis about before their departure. On our way, the only building that survived (was older than 1944) was concentration camp building.
Minsk was rebuilt from ground up, really.
I don't know the real percentage of destroyed buildings in Minsk, but I guess it is about same or even bigger.
I believe the source is Miasto Ruin or City of Ruins [1], which is a CG visualization based on computer modeling of what an airplane would have seen near the end of the war. See also IMDB [2].
Last year I was on a train that went from Germany to Poland, when we were in Poland a girl sitted in the same cabin I was, and asked me something. I said "bitte?" and she was like "we don't like that language, speak in english since you are obviously not german". I said "yeah I'm not german" and we started talking, I was shocked that she, so young, didn't like german language after all these years.
There is a short movie based on a Russian airplane photo footage taken in 1945, the City of Ruins: https://www.youtube.com/watch?v=Vx3aGiurRbQ
The general feeling is also quite well represented in "The Pianist (2002)", which I highly recommend.