Samy, that is a beautiful photograph as was the one you posted earlier. The Nikkor-N 5cm f/1.1 is a cracker of a lens, congrats!
The New Sacristy located down a narrow corridor from the Chapel of the Princes' (posted a few earlier). The entire design is Michelangelo, worked on the project between 1521-1534. There are six marble sculptures by the artist in the small area, it gets crowded here.
The dome's weight savings technique is similar to that used in the Pantheon.
