Interesting link to “ghost pictures.” (From the UK Daily Mail)
A ghost picture is an image usually of soldiers taken in a WW2 location. The picture is then superimposed on the same location as it looks now. The result produces a black and white “ghostly image” over a new color image of the identical location.
An example below.
Superimposed version
The original
History and Hobbies 
This guy does a similar thing…. http://pinterest.com/nickbritten/sergey-larenkov/
Oh yeah, I saw these on a Russian site some time ago. Very interesting. Fascinating stuff. I think you get a real feel for the history. Thanks for the link Nick. Also, I see a lot of history on your Daily Mail and Telegraph. You don’t really see much of that sort of thing here.
It’s fascinating! I’ve recently seen where someone was doing the same thing, only about the San Francisco Earthquake.
It seems to be a developing photographic art form. Thanks J.G.