Commissioned in 1508, the fresco is part of the decoration of a suite of four rooms in the Pontifical Palace — now known as Raphael’s Rooms — that Pope Julius II used as his residence. Along with the Sistine Chapel, these rooms are among the Vatican’s biggest draws. This week the cartoon for the “School of Athens” has gone on public view again after a four-year restoration by the Pinacoteca Ambrosiana, an art gallery in Milan that has had the cartoon in its collection for some 400 years.