It is situated on a huge rock at 589 metres of weight. In its castle was imprisoned the Earl Giuseppe Balsamo, famous as Cagliostro, who died here in 1795.
Due to its impregnable position, San Leo has always been an important civil, military and religious centre.
In the IVth century it was evangelized by San Leone, and conquered by monarchs, dukes and various republics.
From 1632 to 1860 it was a part of the Vatican Reign. Places of interests are the “Pieve”, today a museum, the Pinacoteca” and the Dome, which architectural features melt in an interesting way with the natural surroundings.