I had also seen a similar technique recently with old photos. We searched about for photos where we could make the same effect.
It turns out there’s not enough photos online of Craigmillar Castle, and it’s difficult to find an old and new photo of Edinburgh Castle from the same angle. The Forth Rail Bridge worked quite well, as did the Eiffel Tower and the Great Sphinx of Giza. It’s difficult to find a modern day photo that is larger than the old photo so that you can see the effect.
We then started looking at our final project (our “our mission”!) for the Still Images unit. We researched different designs of drinks bottles and cans as we will be designing our own and creating the marketing for the drink.
Update: I found a lovely blog today called Dear Photograph with lots of nice examples of this technique
Update 6/2/13: Here’s a brilliant image by Danny Charge of Princes Street in Edinburgh