Hi. We are visiting Florence from 10/1 (12:30pm) to 10/5 (leaving 8:30am). I want to purchase the ticket for the Duomo. I have a question about the 72 hour usage. The first Tuesday of the month the Duomo and all of the buildings are closed. If I were to use the ticket on Monday, does Tuesday "count" as part of the 72 hours even though buildings are closed? I'm trying to get the most out of my visit. Thanks!
The only part of the cathedral complex that's closed on first Tuesdays is the museum: the duomo, bell tower, crypt, dome and baptistry are open. To see hours for each, reference the website:
https://www.museumflorence.com
Click the name of each building on the menu bar and then choose your desired date from the "Change day" text under "Opening times" on each page which comes up.
Do understand that you must make reservations to climb the dome, and you cannot do that until you get to Florence if using the FirenzeCard. Also, the clock on the 72 hours starts running when you collect your Grande museo del Duomo free ticket (necessary to make the dome reservation) so it's entirely possible for the life of the card to run out before there's an open time slot for the dome, if that's the very first thing you do when you arrive in Florence.
Read the FAQs of the FirenzeCard carefully, especially "How can I book the Cupola climb with Firenzecard?":
http://www.firenzecard.it/index.php?option=com_content&view=article&id=20&lang=en&Itemid=119