This is a favourite from when I lived in Milan. In 1495, the Duke of Milan decided to decorate the Refectory at the Dominican convent of Santa Maria delle Grazie. He called in the two best artists in Milan to do it. Leonardo da Vinci took the top end, Donato took the opposite. Both artists decided to use the idea of trompe l’oeil.
Leonardo’s painting extends the refectory by three bays, and puts the Last Supper across it, where the top table of the Refectory would go. Donato, instead, imagined that the bottom wall was removed, and the diners could look back to Milan (the convent was then on a little hill outside the walls). And in between them and the city, he put the Crucifixion, with Milan standing in for Jerusalem and the Duke and his family as part of the crowd. It is quite an amazing experience and must have been for the diners, to be seated between the Last Supper and the Crucifixion as if you are present at them.
Donato used standard fresco technique, painting really quickly on wet plaster. His painting has stayed as vibrant and clear as when he painted it. Leonardo, being a genius, tried his own technique of continually applying new wet coats to individual areas so he could take his time. That didn’t work at all, and within a century of it being painted people were complaining that it was fading, dark with mould and hard to see. As they still do now. And it is in constant need of repair. So I’m giving the thumbs up to Donato’s poor relation, which nobody sees unless they go to ‘il Cenacolo”, and turn round.
A last reflection. In the Second World War, an Allied bomb hit the Refectory straight on. It took out all the middle of the building, leaving just a pile of rubble. With the two ends, with their frescoes, miraculously standing. We were that close to never being able to see either of them!