When examining and analyzing buildings, preservationists love to find ghost lines (or marks) that give us clues to where there was once a window, a door, or a change in original construction. These are some very subtle hints on the surface like a change in brick pattern. They are always fun. Imagine my surprise when I saw this while visiting Montreal, Canada with some of the UVM HP students:
This one tells quite the story. Enjoy!
Preservation in Pink 