[lmmlzxx]

A commenter pointed out that one or two of these images appear to be photoshopped, most likely mock ups of a scene that the artist intended to create. The commenter took a lot of heat, but does appear to be correct. The fifth-to-last image (the before) and fourth-to-last (the after) show it pretty clearly if you check out the clouds.

[aquark]

Possibly, but also maybe the other way around. Perhaps they didn't have a before picture of the scene from the right angle, so the before one is photoshopped?

[junke]

Looking at the artist's webpage[0], you can find videos[1] of the work as well as different angles. The before/after effect does look fake, though. I think you are right that the before picture is the one being photoshopped.

[0] http://www.a-fresco.com/pages/ville.html [1] http://www.a-fresco.com/video/video_recre.html

[lmmlzxx]

True, I hadn't thought of that!

[feiss]

Although the first hypothesis looks more plausible.