Nice pics, but as mickmac says, they do look a little like quick snaps, except maybe the first one. If you get a chance to do this over, or try something like this again, then you might want to think about composition, things like "rule of thirds", balance, use of lines to focus the viewer's eye. etc.
The other thing that I would offer, is that a lot of this type of photography, old abandoned buildings, is being done using HDR techniques. You can check out the works of folks like Brian Matiash and Trey Ratcliff.
Cheers,
WesternGuy