A few kilometers from Cavriglia, on the right side of the Arno river valley, the protected area of the Balze is a surprising, small Monument Valley. The best route to explore it is the CAI trail 51 “sentiero dell’acqua zolfina” (trail of the sulphurous water), so called because it partly runs along a sulphurous water source. This ring-trail starts in Castelfranco di Sopra, near the post office, and winds its way through a surreal landscape of natural spiers and cathedrals, surrounded by olive trees and vineyards. The route is 7 km long, including the detour to the charming village of Piantravigne.