You got all the process over there:
Making of: step 1, the shooting
Making of: step 2, the stitching of Paris
Making of: step 3, the rendering
And the photographer interview.
Paris 26 Gigapixels as lived by its photographer Arnaud Frich
If you wondering what French police man are doing by a beautiful sunny day like this, They been flashed
Probably drinking a coffee & smoking a cigarette
I thought exactly the same thing as you NORing when I've found this site. But my house is hidden by another building..
Best regards.
PS