Hello,
Any suggestions on the best way to travel from Siena to FCO airport without a car?
Grazie!
Certainly by train, but it is 4 to 4 1/2 hours. Might be direct buses from Siena to Fiumicino airport.
Bus to Roma Tiburtina station. Then from there either Regional train to airport (station name: Fiumicino Aeroporto) or taxi.
Hopefully you are not thinking of booking a return home flight on the same day from Siena.
You can't get to Rome from Siena (well overstatement obviously -- but it is long and circuitous) It is 90 minutes by fast train from Florence. Consider organize your trip so that your last few days are in Florence and go from there -- or even a last night. It is cheap to go by bus from Siena to Florence, takes about a hour and buses go a couple of times an hour all day and end next to the train station. You could bus to Florence and take a fast train to Rome in less time than going from Rome.
And as others have said -- don't even consider it the day of your flight.