I am tempted to take a road trip. In particular, I'd like to see the burning mines in Centralia, PA and various abandoned tunnels and road bits on the Pennsylvania Turnpike.

As a kid, I had fantasies of digging in my parents' backyard and finding an underground cave or tunnel, either natural or manmade and abandoned. This was not exactly likely in SoCal, given that most development there is new and on granite rockbeds. In Pennsylvania, though, this could very easily happen.