Every photograph you have ever seen of Tuscany with a farmhouse on a bare hill, a winding line of cypresses and a soft haze over rolling fields was probably taken somewhere close to here. The Val d'Orcia is the valley of the river Orcia, south of Siena, a farmed landscape that Renaissance landowners deliberately shaped to look like the paintings of their time. UNESCO listed it in 2004 as a landscape designed with an idea in mind, and on a clear morning that idea is very easy to grasp.
The roads are the real joy. The SP146 from San Quirico d'Orcia toward Pienza and Montepulciano curls along the crests with views on both sides, and the old Via Cassia runs through Torrenieri and San Quirico on the line of the medieval Via Francigena, the pilgrim road to Rome. Corners are open and readable, the surface is mostly good, and the gradients are gentle enough that you can enjoy the scenery without missing an apex. Many of the most famous viewpoints sit at the end of white gravel roads, the strade bianche, which are fine at walking pace but worth treating with respect after rain.
Ride early. The valley is at its finest in the first hour of sunlight, when mist pools in the hollows and the cypresses throw long shadows. In late spring the fields are green and dotted with poppies; in early summer they turn gold; by autumn they are ploughed to bare grey-brown clay, and the place looks like the surface of a gentler moon. Midsummer middays are hot and hazy, and the roads fill with camper vans.
Montalcino, on its hill to the west, is the home of Brunello, one of Italy's great red wines. Bagno Vignoni, a hamlet near San Quirico, has a large thermal pool where the main piazza ought to be, with steam rising off it on cold mornings; the ancient baths are no longer for bathing, but there are modern spas nearby. Further south the hilltop fortress of Radicofani and the dark bulk of Monte Amiata, an extinct volcano, close the horizon.
Fuel is easiest on the main roads and in the larger towns; Chianciano Terme, about twenty kilometres east, is the nearest town of real size, and it is wise not to run low in the valley itself. Pecorino, crusty bread, a plate of pici with garlic and tomato, and a glass of local red make lunch here a lesson in not hurrying.