There is an activity called "Urban Exploring."
I'm not involved with it, but a friend came across the UER site which contained some forums and pictures from locals that do.
This activity is tresspassing in most cases, since all land in the US is owned by somebody, and most of it is somebody other than you.
The upside is these people document landmarks that are generally on their way out, never to be seen again.
This site has photos from the Vault in Norfolk, which was torn down to make way for the Granby Towers condo project. There are some other sites on there as well.
It may be an interesting read to some:http://www.uer.ca/locations/newlist.asp?n=1&statfilter=160&country=United%20States&province=Virginia