
The historical town of San Gimignano on the hill has no train station, but you can easily reach San Gimignano by taking a train to Poggibonsi (labelled "Poggibonsi-S.G.") and then a bus from the Poggibonsi train station to San Gimignano. These buses cost €3.60 (2007) each way, leave every 30-40 minutes, and you can inquire for information, schedules, and tickets at the tourist information office which is located ahead toward the right as you walk out of the train station.
If you are going from Florence (Firenze) to Poggibonsi, direct trains are not so frequent but you will find many connections via Empoli.
Easily reachable from Florence or Siena, though you may have to change buses in Poggibonsi. Buses leave from Florence's bus station (next to the train station) hourly, and take 1.25 to 2 hours for €6. From Siena there are €5.20, 75 minute buse rides (5 a day)
Buses depart from Porta San Giovanni, with tickets sold at the bar just inside the gate or at the Tourist Info. Florence buses leave hourly, change in Poggibonsi, and take 1.25-2 hours. Siena buses are 5/day, 75 minutes, and also change in Poggibonsi. Volterra has 4/day that take 2 hours and change in Colle di Val d'Elsa. Sunday buses are fewer and more crowded.
You may also arrive by car. You can't drive inside the town walls, but there are several pay parking lots just outside the town walls, with free places further away. The handiest lot ,Parcheggio Montemaggio, outside Porta San Giovanni, fills quickly, but they let 1 car in for every one that leaves, so you can wait (€2/hour).
On foot - it's very small, and you must disembark from your car or bus outside the city walls, in any case. An electric shuttlebus goes all day from Porta San Giovanni to Piazza della Cisterna to Porta San Matteo. €.50, 2/hour, buy ticket at Tourist Info or Tabbachi shop
You will notice shops where free wine tastings are offered. If you consider the wines a good value, buy some bottles. You may find the wine expensive.