It is the oldest of Porto Ercole's three fortresses (the other two being Forte Filippo and Forte Stella), whose origins date back to the medieval age, to the Aldobrandeschi family, although at the time it was a paltry thing compared to the size and complexity it achieved over time. The enlargements and transformation into a real fortress actually began in the 15th century with the arrival of the Sienese; the present appearance, of a real fortified citadel, however, is due to the Spanish, who took possession of it from the 16th century. The complexity and vastness of the construction can be perceived only from a distance, particularly from Fort Philip and Fort Stella, together with which it formed a single system of sighting and defense/offense. Today the complex is almost entirely private (rooms that once had military purposes and, for a time from the late 1800s, also used as a prison, have been converted into housing) and access to the interior is not free; it can be visited at certain times with a municipal permit obtainable through the tourist office. The castle can be reached by a detour to the left from the Panoramic road that circumnavigates Mount Argentario, shortly after leaving, also on the left, the entrance to the ancient center of Porto Ercole (Porta Senese). Of course once you get there, if you cannot enter the interior there is very little to see.
