Trevi nel Lazio is a summer holiday resort and ever since ancient times has been the main centre and administrative point of reference for the whole of the Aniene Valley. The origins of Caetani Castle are unknown, but it was probably founded after the year 1000, on a roman stronghold.
In 1257 Pope Alessandro IV gave his nephew Rinaldo de Rubeis the fief of the area of Trevi, including its castle. In 1262 with the Pope Urbano IV, the fief was given to the Subiaco monastery. From this point on the owners of the Castle were by turns the papacy or the De Rubeis family until 1299 when Pietro Caetani, brother of Bonifacio VIII, bought it. Under Caetani rule the Castle, experienced a period of great splendour which ended in 1471 when Cristoforo Caetani was driven out of the town for misgovernment. In 1473 Trevi was given back to the monastery of Subiaco and the Castle became the Curia centre; in 1753 Benedetto XIV gave the town a different administrative organisation and the Castle lost its representative role furthermore, as years went by more and more buildings in the village were built in close proximity to the castle walls, there by reducing its defensive capacity. In 1915, after the earthquake, all the village was rebuilt and a section of the Castle was included in the nearest buildings. The Fortress was subsequently abandoned and some of its walls and wooden lofts collapsed. In 1984 restoration work began on the castle and as a result the castle has long since won back its old splendour.