Museum Cappella de' Pazzi in Florence

You're standing in the first cloister of Santa Croce, on the south side of the great basilica. In front of you is a modest little building with a columned porch. That's the Pazzi Chapel, one of the masterpieces of early Renaissance architecture. Take a good look at the front. Behind the porch, which was added later, you can still make out the lower part of an older façade. Brunelleschi may well have started that one himself.