The closest airports are Florence (FLR), Pisa International Airport (PSA), and Rome Leonardo da Vinci–Fiumicino Airport (FCO). Flying into either Pisa or Rome will require you to make your own travel arrangements either to Florence or to the Castello.
Transportation will be provided from the Florence Airport (FLR) to Castello di Ristonchi in two-waves in the afternoon of Friday, September 19th. Your bus number and departure time will be assigned to you with your invitation.
You can get to the airport by taxi or through public transportation from the Santa Maria Novella train station taking the T2 tram. The ticket price is roughly €2 and departs every 5-10 minutes during peak hours.
Please check your passport expiration date ASAP. It must be valid for at least 6 months after your return date to the United States. If you do not have a passport, start applying now! Double-check that you have signed your passport.
Europe has postponed their pre-departure digital "visa" system - ETIAS until 2026! No further action is needed prior to wedding travel.