Quote -  yeah
you'd need to bring in the buildings in as a separate layer and work on that.

i wouldn't use the eraser tool, i'd use the masking tool cause it's non-destructive and you can change your mind if you want (can't do that if you've eliminated the pixel information).

look at old buildings to see how the decay looks like. it shouldn't be too difficult to replicate.

:)
retrocity

I'm totally clueless when it comes to the masking tool.  Any suggestions on how to learn how to use it other than me searching "photoshop masking tool tutorials."  Is there a specific  type of masking tutorial that I should be looking for or, is it just best to start from the beginning?