If you decide to visit the valley that is one of the most popular postcards of Tuscany - the Val d'Orcia, of course - add a day to explore Bagno Vignoni. This village is different from the others: what in traditional towns is a main square, in Bagno Vignoni is a pool 49 meters long and 29 wide, from the bottom of which bubble up a number of hot springs whose therapeutic quality has been renowned since antiquity.
Don't forget to bring an old swim-suite and a towel to Bagno Vignoni. You cannot have a bath at the main square pool, but if you go down to the Parco dei Mulini you can relax at a spring of naturally hot water. Important: there is no ticket to pay, you can enter for free!
While you are relaxing there you can try to imagine to be in the past: Bagno Vignoni was a halting and refreshment point for numerous pilgrims who traveled the Via Francigena on their way to Rome, one of the main destinations for the Christian pilgrimages.