I know I'm slow finding things sometimes, but just ran across two web sites that are really interesting. You can take an image and pin it to a mapping site to see what the current address used to look like. Don't laugh; I'm sure they've been there for ages and I'm just finding out! www.whatwasthere.com is a really neat site for this. There are tons and tons of images already there and I love pulling up an address (say Historic Downtown Charleston) and seeing an image from the past overlayed on the current street view of Google Maps! You can slide a bar that fades the image in and out to make is easier to view.
Another similar site is www.historypin.com
I'm a visual type of person so being able to see old images overlayed on current images makes it so much more easier for me. Try it....I'll bet you will be addicted!