Coming from North
We suggest to follow the "A1 - Autostrada del sole" highway until "Firenze-Certosa" and then the road to Siena. There are two different roads, one is fast and directly goes to Siena, the other one follows the hills of Chianti and touches many nice towns.
Arrived in Siena, you have to exit at "Siena sud" and take the "SS 2 - Cassia", direction Monteroni d'Arbia, Buonconvento and San Quirico d'Orcia.

Coming from South
The better road is follow the " A1 - Autostrada del sole " until "Chiusi-Chianciano Terme and then follow the road to Chianciano-Siena. Before Chianciano turn right at the first crossroad and follow the indication to Bagno Vignoni, SS2 Cassia and San Quirico d'Orcia.