The Chapel of San Michele Arcangelo was built in 1597 by the architect Santi di Tito and is a perfect reproduction on a 1:8 scale of the Cupola del Duomo of Florence. It rises near the place where the Florentines destroyed the castle of Semifonte in 1202.

The phenomenon of the construction of castles in the Val d'Elsa dates to the domination by the Alberti family around the XII century. The castle of Semifonte was one of the last to be raised. Maybe it was for this reason that this town remained one of the last feudal strongholds at the time of the city-states' autonomy development, and it acquired a remarkable power. Its expansionist views on the countryside, that the Florentines were contending for with the important families of the rural aristocracy, led it to a fatal clash with Florence.
The castle of Semifonte benefited from a particular strategic position and it pursued an open policy that made it one of the "free trade zones" in Tuscany, where exiles, drifters and wanted people found a refuge. It was for this characteristic that it earned the hostility and the antipathy of Florence and Siena. Its renown as a refuge caused a sensible increase in its population until 1180-1200, when Semifonte had as many inhabitants as Florence.
The castle of Semifonte, that was very populated and backed by the Germanic emperor Henry IV from an anti-communal viewpoint, became famous in the whole Valdelsa for its irreverent and hostile behaviour towards Florence.
The legend tells that its inhabitants walked until the walls of the powerful Tuscan city while singing the refrain: "Firenze fatti in lą, Semifonte si fa cittą" . It is not possible to determine if this episode roused the anger of the Florentines, who besieged the fortress in 1202 and conquered it.
Semifonte was completely razed to the ground, to the extent that it is almost impossible to locate the evidences of the ancient castle's presence today, even to experts. From the remains, it can be imagined that the citadel was composed of a three-kilometre wall and of a castle overlooked by a keep.
The Florentines were not totally satisfied of their actions and decided that the castle was not to be rebuilt and that all those who survived had to move elsewhere.
The Lorraine conceded one exception to the edict of Florence in 1587. These new rulers, who had just arrived in Florence, commissioned Santi di Tito to build an octagonal dome as a small-scale copy of the Brunelleschi' s Florentine one and decided it to be built in Semifonte. The chapel was dedicated to san Michele Arcangelo. Coming here, there is the possibility to admire the wonderful landscape once dominated by Semifonte.