Sonnino is a splendid medieval village perched on the summit of Colle Sant’Angelo in the Ausoni Mountains overlooking the Amaseno Valley and the Tyrrhenian coast. Due to its strategic position, the area was already inhabited by the Volsci in the pre-Roman period, and the legend of Queen Camilla of the Volsci arose here and her story is told in Virgil's Aeneid.
When her father was driven from his city Privernum and was chased by his enemies, he tied little Camilla to a spear which he threw onto the other side of the river and so saved her. Then he educated her as a warrior and Camilla became the best. In the end ishe would be defeated by an Etruscan warrior thereby changing the course of history for the Volsci and the populations of southern Lazio.
The presence of Volsca is evidenced by some archaeological finds and by the name of the access road to the village which is still called Via Volsca.
When the Romans arrived, this area assumed a certain importance and Privernum was equipped with all the modern Roman infrastructures. With the fall of the Roman Empire, maintenance work on the water distribution system ended, the plain flooded again and the Via Appia was no longer viable for a long stretch. Mountain roads were back in operation.
According to legend, Sonnino was founded in the 8th century when the inhabitants of the lower Priverno took refuge in the hills around a fortified "castrum" to escape the invasions by the barbarians and Saracens. In general, these castrum structures consisted of a tall tower, which was part of a defensive sighting system, and a protective wall.
This small castle was located on the top of Colle Sant’Angelo, one of the offshoots of Monte Ceraso. It seems that the name Sonnino derives from the word ‘summit’ to indicate that the town was built on a mountain.
Many invaders succeeded in controlling this area starting with the Goths and then the Lombards who had moments of great splendour in the Duchy of Benevento, and finally with the Saracens arriving from the sea in the IX century.
The first document in which Sonnino is mentioned is a papal bull of 999 and at that time the communities were formed around a small castle and a church. The first lords of Sonnino were the De Sompenino, whose name probably comes from that of the village of Sonnino.
The first municipal statute dates back to the 13th century and is kept in the State Archive in Rome. Sonnino has always belonged to the Papal States and was part of the provinces of Campagna and Marittima until 1870.
From 1369 the castle was purchased for 2000 florins by Onorato I Caetani, who were originally from Gaeta as can be understood from their name. Later many families followed, such as the Caetani of Aragon and the Borgias of Pope Alexander VI for a short period. On the death of Pope Borgia, the Colonna family took over Sonnino in 1503 and kept it until 1816.
Sonnino has always been part of the Papal State and entered the Kingdom of Italy in 1870, but its position as a border country with the Bourbon Kingdom has characterized its history and that of banditry. For some years Sonnino was the town of bandits and in 1819 an edict of Cardinal Consalvi ordered the destruction of the town which was stopped only by Cardinal Giacomo Antonelli, Vatican Secretary of State who was originally from Sonnino.
In the interesting Museum of the Borderlands these stories are narrated and in particular that of the Bandit Gasbarrone, perhaps a hero, a modern Robin Hood who, once captured and imprisoned, had become so famous to receive letters from women from all over Europe.