The Lost Paris
This isn't my photograph, I include it here because it is interesting and here is a link to a page where I will post more. What it is, is one of the photographs taken by Charles Marville in the years 1852 - 1870, before Paris was demolished to make way for the boulevards.
It was Eric on this post that made me think of these. Quite a few of the photos in my book have ghosts, too.