Last week, I was in the Florence Baptistery by 8.30 a.m. That used to be early enough to avoid the crowds and admire the Baptistery’s east doors by Ghiberti — the Gates of Paradise, as Michel-angelo called them.

No longer. As I stared at the 13th-century mosaics in the apse and Donatello and Michelozzo’s tomb of Antipope John XXIII, a group of bored Italian teenagers started hugging each other and gossiping on the front pew next to me.