I don't really understand why people put Hamburg on the list of the cities lost during the Second World War. Most of the old, half-timbered, hanseatic Hamburg was lost in the 1842 fire, and in the following decades when much of the center was redeveloped (to such a massive scale that the city, officially referred to as the "Hanseatic City of Hamburg", came to be nicknamed "Demolished City of Hamburg"). The Hamburg that the British bombers found was essentially a modern city, and even so, the bombing of Hamburg was different than that of other cities, in that the areas most affected were densely-populated working-class neighborhoods rather than the center. Even in the center, many of the buildings that were damaged were made of stone rather than wood, and thus the outer walls remained standing and were more easily salvaged afterwards.
This particularity explains the huge death toll, and it also, perhaps ironically, means that, among German cities, Hamburg actually has one of the highest concentrations of pre-war buildings in its center, with the caveat that they are mostly buildings from the late 19th and early 20th century. Many streets in the old town area are lined up with very interesting pre-war buildings (just check the list of architectural monuments to convince yourselves), but because they're fairly modern, they do not appear to have the old world charm that one associates with Germany.
Hamburg is definitely one of the most beautiful and architecturally-rich major German cities, alongside Munich.
This. Agree 100%, of the German speaking bigger cities, Hamburg is up there with Vienna, Munich and Leipzig in terms of best preserved centre and general character of the city. Although operation "Gomorrah" was the deadliest singular attack on a German city in WW2, causing basically a quarter of the built area to go up in flames in the course of a week in the summer of 1943, it hit the workers' quarters in the Eastern and Southeastern parts of the city hardest.
In addition to that, as you said, Hamburg had either lost or replaced almost all of its "combustible", typically German city centre before anyway, so that most of the centre consisted of thoroughly-built Gründerzeit architecture which survived WW2 surprisingly well, same goes for the UNESCO areas of brick expressionism (Kontorhausviertel) and the Speicherstadt that both survived largely unscathed.
On top of that, Hamburg boasts one of the most extensive and well preserved Gründerzeit residential areas in all of Germany with a very unique style of building, a large part of the districts of Winterhude, Harvestehude, Eimsbüttel and Ottensen, Altona and Eppendorf are very well preserved with either all-white or a very elegant red-and-white style of Gründerzeit town extension which is a must-see for every lover of this style of architecture, the area around Isestraße, Klosterstern, Hochallee, incredible while at the same time extremely urban, somewhere in the German part of this forum, there was a guy that had used some tool to calculate population density and the area north of the Alster (basically Winterhude) had the highest density found in any German city.
I still haven't found the time to shoot some photos, but I will one day to show you.
Hamburg, although logically and geographically being one of the prime targets of the Allied bomber raids, and despite the catastrophic destruction in its Eastern half (which still is a rather dreary sight) is probably one of the cities that lost the least in terms of serious pre-war sights in Germany, it's basically all still there, or at least more than in almost any other city with the notable exception of Leipzig and Munich, maybe.