topgas, your "after" picture well illustrates how little Paris changed as a result of the war, thanks to having been an open city (though of course, Hitler had called for it to be laid waste as the liberating allied armies advanced towards it. An order that was defied by its resident Wehrmacht General). Contrast that with London and many other UK cities and towns, where the bombsites have long since given way to 50s infill, in stark contrast to the Victorian and Edwardian terraces or villas on either side. The same is true of course for German towns and cities. Indeed, it is more so for instance in West Berlin which now features much post war dreary architecture, in stark contrast to the more classical buildings still to be found in the east, where patch and mend was favoured if only on a purely economic basis.
Such reminders of the effect of war are salutary, and a constant reminder of its devastating effect. Younger generations need the memorials and other reminders of it to learn that simple lesson, be it a grand public monument or a simple house that just doesn't quite fit in with its neighbours.