After the Battle, a British WWII history magazine has been doing this for years, since the mid-1970s. They gather a mess of photos from various archives and then go to the battlefields, cities, etc, and take photos of the same spot (as close as possible--often new construction will prevent an exact comparison), and combine those images with excellent historical text. The results are amazing. And not all the scars of war have been eradicated--many buildings still bear the marks of shell and gun fire which can be seen in the wartime photos. It's also amazing how much was NOT affected, i.e. destroyed, during the war and is still around today for these comparison shots.