What happened to Warsaw's old town in the war?

It was destroyed deliberately, after the fighting was over. Following the 1944 Warsaw Uprising, German forces spent months systematically demolishing the city with explosives and flamethrowers, building by building, on Hitler's order that it be erased - not as a by-product of combat but as a punishment. Something like 85 per cent of Warsaw was rubble by January 1945.

It was then rebuilt from pictures. The reconstruction of the old town used the eighteenth-century cityscapes of Bernardo Bellotto, painted with such topographical precision that they could serve as architectural references, along with pre-war photographs and surviving student measurement drawings made in the 1930s. What stands today is a 1950s reconstruction of an eighteenth-century view of a medieval town.

UNESCO listed it in 1980, which required an argument. World Heritage status normally depends on authenticity of fabric, and this is by definition a replica. It was inscribed anyway, on the reasoning that the reconstruction itself was the significant thing - an outstanding example of a nation deliberately rebuilding its own memory after a deliberate attempt to erase it.