Sure, it would be possible, but I don't think anyone would look out them very much. The view would not be very exciting. Just blue sky or clouds, and not able to see the ground.
On large aircraft like the 747, the existing ceiling in the passenger cabin is not very close to the top of the aircraft. This is based on seeing inside the shuttle carrier 747 aircraft and seeing how tall the fuselage frames are when their is no interior in the airplane.
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.