I have a confession to make: I'm addicted to old buildings. (Perhaps you've noticed.) Abandoned, decaying old buildings are even more fascinating because their tragically desolate presence begs you to imagine what they must have looked like back when they were inhabited and appreciated. Who was here last? And when?
(Rehabbed old buildings always seem a little bit fake: either they've been remodeled and re-remodeled so often that they're beyond recognition, or they've been painstakingly restored practically to mint condition by some historical preservation group and thus are used only as museums to themselves.)
Such architectural ghosts of the past tend to recede into the background when you're zipping along in a metal box, but in the open environment on a bike or your own two feet you're forced to confront them, face to facade, on their terms. You can't help but wonder, what was this place? And what am I doing here now?
Capturing that mood with a camera is a challenge. I've run into a couple of Web sites that take that challenge and eat it for breakfast; one is Detroit Ruins and one is Sonic Atrophy. If you know of any others, pass the URLs along and I'll see about sticking a collection in the sidebar.
Update: Here's Forgotten Chicago.