Amazing photos. I saw something like this done with the Leningrad siege. You might like to check it out! Leningrad: back then and now (99 pics) - Izismile.com
On a few of them he should have made the historic overlay more opaque, but overall its a very nice set. There are a few of us here that have done the same. Jagdpanther44 (if memory serves me right) had some good ones -- try a forum search for "then and now" and you should find a few results.
Very nice pictures. I'm a sucker for then and now pictures. It would have been nice to see the individual pictures before they were "blended", but that's just me. There are several of these then and now throughout the forum.
You can find a lot more of Jo Teuwisse's work here and here. She has many hundreds of photos, both original and altered.