There are Tuscan landscapes dominated by barren hills that glow white when the sun shines high in the sky, drying their clay. In Val d’Orcia, particularly in the Crete Senesi area, it's not uncommon to encounter these formations that are called Biancane given their appearance.
The Accona Desert and the Biancane di Leonina are among the naturalistic sites of noted importance and visual impact, extending into the territory of Asciano.
The formation of this particular type of relief dates back to the Pliocene period about 4 million years ago when this area was the backdrop to the Tyrrhenian Sea. Even today, the soil retains traces of rock salt. You can explore the area by following the CAI 003 path, known as the Ring Route of the Biancane di Leonina, which also leads near to the Site Transitoire and along the Via Lauretana, the historic communication road that crosses the whole area and connects Siena to Cortona.
The Biancane di Leonina are almost completely bare: the uniqueness of the land means that they are not suitable for the growth of trees and shrubs, but only sparse vegetation that covers them like a thin veil. Looking beyond these reliefs, you can see the cultivated fields and the ravines, rugged rock formations that create ridges in the ground created following erosion caused by the waters.
Overlooking the Biancane di Leonina is the castle of the same name, an architectural complex created as a Sienese bulwark and later transformed into a fortified farm that's now an accommodation facility.