In fact, Rocca di Papa occupies the territories once belonging to the ancient Albalonga and to the ancient College of the Sacerdotes Cabenses, who followed the cult of Jupiter Latiaris and the Virgines Arcis Albanae, from which the Vestals founded by Numa Pompilius, originated.
According to recent studies the present day living area coincides with the Latin city of Cabumand the fortress that still overlooks the town today used to occupy the ancient acropolis. But the real living nucleus of Rocca di Papa only started in Medieval times: initially it was fief of the Counts of Tusculum and later of the Annibaldi family.
In 1328, Louis IV Emperor of the Holy Roman Empire besieged the town. The traces of that time are still visible in the blue and white colours in the town banner. During the Western Schism (1378-1417), the territory became property of the Orsini family and once again of the Annibaldi family and in 1427 was purchased by the Colonna family who ruled it until the second half of the 19th century.
In 1527, after the Sack of Rome, the stronghold of Rocca di Papa was used as a prison for the soldiers of Emperor Charles V. Thirty years later, the stronghold was destroyed in the war between Velletri and Colonna. Rebuilt once again, it underwent a peaceful period until 1814 when the ownership passed from the Colonna family to the Church.
In 1855, the citizens rebelled against the Church and proclaimed the Republic of Rocca di Papa of which there is no clear information.
During the year of the Grand Tour, numerous writers stayed atRocca di Papa such as Goethe, Hans Christian Andersen and Stendhal who described Monte Cavo in his short novel La Badessa di Castro (1839). During the last years of the 19th century, near the ancient fortress, the Royal Geodynamic Observatory was built and used by Gugliemo Marconi for his scientific experiments on radio transmission from 1922 to 1935.