Leonardo da Vinci studied Ghirlandaio's fresco depiction of the Last Supper which can be viewed on specific days in the cloister of the Chiesa di Ognissanti in Florence. I haven't seen Leonardo's famous rendition in person, but I suspect that Ghirlandaio's is the more beautiful example, while that of da Vinci will necessarily be more symbolic and enlightened.

Surprisingly, non-flash photographs were allowed in the cloister chapel.

In the actual church of Ognissanti - which translates as All Saints - is a rather good painting by Ghirlandaio of Saint Jerome / Geronimo / Gerolamo.