Historic buildings from Ireland to Russia to Greece were completely devastated. I will even include Spain as well. Obviously Germany, the Netherlands, and Poland were especially hard hit.
While many destroyed historic buildings were just leveled and newer, modern buildings put in their place, there are lots of buildings that were "reconstructed" to look like nothing ever happened. Is there some unspoken rule to just gloss over that the "old" building you are looking at is a modern replica? Do historians you know of look at these buildings as "authentic enough"?
I know I cringe whenever I read someone talk about "historic Rotterdam" or "The historic buildings of Warsaw", showing buildings that are just recreations of the ones that were destroyed in the 40s.
I think you are overestimating the number of cities that were thoroughly destroyed during World War II. Indeed, even though Germany and Poland were two of the countries hardest hit by wartime destruction, both countries have a large number of towns and cities that were largely left unharmed or left in a state that allowed damage to be repaired instead of the buildings having to be completely rebuilt.
In most cases you can easily see which category a given city is in by looking at the size of the old, historic core of the city. Warsaw and Dresden, which were both mostly destroyed during the war, have small, rebuilt cores at the center of a large, modern city. On the other hand, cities such as Krakow or Prague have large intact old towns, because they largely managed to escape destruction (and, as mentioned, individual buildings that were damaged were often in a state allowing them to be repaired).
Indeed, complete devastation was probably the exception rather than the norm in World War 2. Rotterdam and Warsaw are two particularly famous examples of mostly leveled cities (Berlin and Dresden are two other famous examples), but few cities in France, Spain (which didn't participate in the war, but perhaps you're thinking of the Civil War?), Italy, Denmark or Norway or Britain faced such a fate.