Even on a tight schedule, San Lorenzo & Medici Chapels earns the hours.
Allow 1.5–2 hours for both.
The New Sacristy is the reason, and it's haunting in a specific way: Michelangelo designed the whole room — walls, light, tombs — as one composition, and the four allegories of Day, Night, Dawn and Dusk sprawl half-awake over the Medici sarcophagi, muscular and melancholic, as if mourning is a physical weight. Night, the woman with the owl and mask beneath her, is one of the most copied figures in Western art. You stand in a cool grey-and-white room he never finished and feel his grief management for a dead dynasty. The lavish marble Chapel of the Princes next door is the opposite — overwhelming Baroque bling. Plan which parts you're paying for: basilica, Laurentian Library and Medici Chapels ticket separately.