The Michelangelo facade of San Lorenzo projection is Saturday and Sunday night. We went to see it tonight but it starts tomorrow - sorry if anyone else went tonight on our advice! There is a giant marble column outside the church which is said to come from the never realized project. Pictures coming of that.
I found out that entering the "centro" from Via de'Benci is not allowed - I just received 4 tickets of about €65 each... and I fear more are on the way (these first ones are from October and November when we first got the car). Never drive across the Ponte Alle Grazie and proceed straight on Via de'Benci - turn right (along the river), and come in by the Biblioteca Nazionale (map here).