The Fort defended Nettuno from sea raids. Inside the fort in a central position stood the Keep, subsequently enlarged with additional floors to accommodate a larger garrison. After the Borgia’s, the Colonna owned the Fort until 1594, when they handed it over to the Apostolic Chambers. After alternating fortunes, the castle was passed down to the Borghese Princes in 1831.

 

On the 20th of July 1925 it witnessed the signing by Benito Mussolini of the convention between Italy and Yugoslavia regarding Italians in Dalmatia. In 1931 it was bought by the Baron Fassini, who invited Queen Mary of Rumania and the Princess Ileana.

 

Now the building belongs to the Municipality and also houses the “Museum of the Allied Landing” and the Antiquarium, and many conferences and art shows take place here. A very accurate study published in 1990 by the architect Cesare Puccillo with the title “Nettuno, a mainstay of the coastline defensive system of the Pontifical State – The Borgia Fortress”.