These maps of cities based solely on photo density are amazing to look at. From the photographer who created these ghostly beauties:

“I got the photo locations from the Flickr and Picasa search APIs. The base maps that they are plotted on top of are from OpenStreetMap. I wrote some perl scripts to identify and plot the clusters of locations. The scripts generate PostScript which I then converted to JPEGs using Ghostscript.”

Amazing what we can see when we look at things in a new light.  Here’s San Francicso (visit the site to see Paris, Tokyo and more):

via Flowing Data’s World atlas of Flickr geotaggers.