Florence's sights keep tricky hours. Some are closed Wednesday, some Monday, some every other Monday. Quite a few shut their doors each day (or on most days) by 2 in the afternoon. Things get even more confusing on weekends. Make it a general rule to check the hours closely for any place you're planning to visit; if it's someplace you have your heart set on seeing, it's worthwhile to call to confirm.
Here's a selection of major sights that might not be open when you'd expect. And be aware that, as always, hours can and do change.
The Accademia and the Uffizi are both closed Monday.
The Battistero is open from 11 until 7, Monday through Saturday, and Sunday from 8:30 to 2.
The Bargello closes at 1:50 pm, and is closed entirely on alternating Sundays and Mondays. However, it’s often open much later during high season and when there’s a special exhibition on.
The Cappelle Medicee are closed alternating Sundays and Mondays (those Sundays and Mondays when the Bargello is open).
The Duomo closes at 4 Thursday (as opposed to 5 other weekdays, 4:45 Saturday, and Sunday it’s open only from 1:30 to 4:45). The dome of the Duomo is closed Sunday.
Museo di San Marco closes at 1:50 weekdays but stays open until 7 weekends—except for alternating Sundays and Mondays, when it's closed entirely.
Palazzo Medici-Riccardi is closed Wednesday.