Google released historical imagery in Google Earth of 35 European cities as they looked during WWII. Today, Google announced that they have added to Google Earth even more historical imagery of London and Paris. This imagery like the imagery in the previous release is aerial imagery that can be accessed by opening the time slider in Google Earth. If you don't know how to open the time slider, see the image below.
Applications for Education
Many times I've had students comment to me that exploring Google Earth and Google Maps has been very helpful for them in recalling information about our history lessons. The historical imagery can be useful for providing students with geolocated imagery to aid in recall of information about historical events.
Here are some related items that may be of interest to you:
How to Make Placemarks and Tours in Google Earth
Google Earth Across the Curriculum
Free 33 Page Guide - Google for Teachers