After the Middle Ages Sestino lived a new successful season in the sixteenth century with the construction of the "City of the Sun" on top of the Sasso di Simone, ambitious project wanted by Cosimo de' Medici to defend Tuscany against the expansionist ambitions of the dukes of nearby Urbino.
The territory of Sestino is very rich both in nature and history. Not to be missed are the majestic Sasso di Simone and the smaller Simoncello, two huge limestone blocks that with their imposing size dominate the territory, and the Wildlife Park of Ranco Spinoso, where deer, deer and mouflon live in the semi-wild state.