(Updated Sept 19, 2021)
On the eighth day, God created a direct bus service between Rome Fiumicino airport (FCO) and Siena. Once operated by a separate service (formerly known as Sena Bus), this inexpensive route is now operated as an arm of Tuscany’s Tiemme system. The schedule is virtually the same. For those not driving, I recommend this direct bus as the easiest, fastest, and cheapest transit route between Rome airport and Siena. The bus schedule for this direct service is found here. A screen shot of the schedule is below, followed by some tips on how to interpret the Italian site.
NOTE: The second daily bus in each direction appears to have been cancelled as of Sept, 2021 (listed as ore 15.15, or 3:15pm departure from Siena).
Translating the Schedule: The two sections above include Departures (Hours) from Siena to FCO, and from FCO to Siena. There is one daily bus per day in each direction (the afternoon/evening buses listed above appear to have been cancelled). From Siena southbound they depart at 6:15 am from Piazzale Rosselli, just outside the Siena FS (train) station. Next stop is Piazza Gramsci ten minutes later at 6:25 am (see Orari da Siena above). You can board the bus either at its point of origin at the train station, or when it stops at Platform 3 at the Piazza Gramsci bus terminal (see my post about Piazza Gramsci). The bus arrives at Terminal 3 at Rome’s FCO airport at 9:30 am (presuming no traffic problems). Cost for a one-way ticket is 22 euro per person, much cheaper than the train.
From FCO Airport to Siena, the bus leaves the airport each day at 10:45 am from Stall 10 (typically) outside the entrance to Terminal 3. It arrives in Siena’s Piazza Gramsci at 1:50 pm. Ten minutes later the bus arrives at its final destination at Siena’s FS train station. (But if you are planning to stay in the city’s historic center, Piazza Gramsci is the closest place to disembark. Don’t continue on to the station.)
TOM’S TIPS: We have taken this bus both ways numerous times since 2014, and it is wonderful. Direct service between FCO terminal 3 and Siena’s two main transit destinations. Buses are high-quality motor coaches with optional curtains to block the sun. As indicated on the schedule, the bus makes three other stops (including Grosseto) along the way. Usually only a handful of people board the bus at its origin in Siena (the 6:15/25 bus, that is), so we have never experienced overcrowding. Plenty choice of seats. If you take the 6:15 bus to FCO, however, you can cut it close with flights that leave between 11:00 and 12:00. With only 1.5 – 2 hours between the bus arrival at FCO and your international flight, you risk not making it through the airport gauntlet in time. For 11am flight departures, we stay overnight in Rome to calm our nerves. Yes, you might make it if all works well (we did once), so it depends on whether you are feeling lucky.
TICKETS: You can purchase bus tickets a day or two in advance at the ticket office beneath Piazza Gramsci. If you take this option to assure your seat(s) from Siena, they will ask for your name and time/day of departure so that the driver will be expecting you. The driver will check you off his/her list when you arrive at the bus (this is my experience, anyway). You can also buy tickets (same cost, 22 euro/person) directly from the driver. This is typically necessary for the FCO Airport to Siena bus, when departing baggage claim to catch your bus. Without tickets in advance, you can find the bus (usually at Stall 10, but check around if necessary) and simply pay the driver. I have never known this bus to be packed in either direction, so I have full confidence taking this approach (if someone has experienced otherwise, please send me a comment).
What happens if you miss your bus from FCO airport? You have two other transit options to get to Siena the day of your arrival: Trenitalia train service, or Flixbus from Rome Tiburtina (take train from FCO Terminal 3 to Rome Tiburtina to catch the Siena bus across the street from the station). Either way, you will get to Siena at some point to begin your magical visit!