Sorry Hans, they're not downloadable.
There are some useful tools for viewing:if you click on the "Immagini affiancate" icon (2nd from left, top left corner), you can get a twin view of orthophoto & 1:25.000, or B/W orthophoto & colour orthophotos, as you wish.
Moreover, clicking on the "Immagini sovrapposte" icon (3rd from left, top left corner) you will get an overlay view. It's very useful to overlay orthophotos with IGM maps, so you can see the name of the places on the photos!