I’m going to be visiting Frankfurt - one of my favourite German cities - in not quite two weeks; and I just came across a website that describes how Frankfurt was rebuilt after WWII. Unfortunately, it’s in German only. The photos are here, and it’s more or less straightforward to look through the photos, given the dates next to the links. There are also links that show some of the places today. For that, click on the yellow links next to the photos that say “heute”.
Highlights: Reconstruction of the city center (with drastic photos of the destruction and the replacement of those destroyed quaint houses with hideous 1950’s blocks), technical reconstructions (with cool/weird 1950’s technology), the shopping district, and - especially cool: “modern” architecture 1949-53, 1954-59, and 1960-66.