Golden Gate Park

At Golden Gate Park, there was this picture, probably 10 feet long x 6 feet tall.  It is similar to a Hologram, but it's made out of glass.  If you start on the left side of the picture and work to the right, the picture changes to depict what the bay looked like before the bridge was started and over the years of construction. 

There is just one picture, or one frame hanging on the wall, but as you walk past it, the images change to show the construction.  One of the most interesting things I have ever seen to show the history of a place.