The [This Week in Photography](http://twipphoto.com/) podcast mentioned a few great photo sites. The sites specialize in abandoned, forgotten or unexplored areas of the urban landscape. Very interesting pictures/blogs. Enjoy!
[Sleep City: Urban photography, urban exploration](http://sleepycity.net/index.php)
[Opacity: Abandoned Photography and Urban Exploration](http://www.opacity.us/)
Check out this amazing photograph from the [Paris catacombs](http://sleepycity.net/photo/1359/in/location/Paris).
