If you plan to visit museums in Florence, you might want to consider buying the Firenze Card, a pass good for museum entrances and public transportation, valid for 72 hours.
Why Buy a Firenze Card?
Buying a Firenze Card could save you time and money (depending on how many museums you visit) since you've already pre-paid and don't have to stand in ticket lines, reserve ahead, or buy each ticket separately. Also included is admission to any special exhibits so there's no additional charge. Note that some of the monuments and museums on the pass are already free.
Using the Firenze Card
When you get the card, write your name on it immediately. At the entrance to a museum or monument, look for the Firenze Card sign and show your pass there for admission. On a bus, swipe the card against the validation machine inside the bus. Validity starts with the first use of the card and will be good for 72 hours with one admission to each of the listed venues. Card must be validated within one month from when you pick it up.
What Museums are Included?
With a Firenze Card you get entrance to more than 30 museums, monuments, and gardens including these favorites:
How To Buy a Firenze Card
Current cost (2014) is 72 euro. You can check updated prices and buy the card online on the Firenze Card web site or at a museum or tourist information point. If you buy it online, check the collection points on the web site to see where to pick it up.