The Rocca building was probably built in the 14th century, overlooking the sea on pre-existing structures of a beautiful Roman villa and on the polygonal walls of the castrum from the 3rd century BC.

Its current appearance is the result of a series of modifications made up to the 18th century. On the outside it is characterised by two circular towers and two rectangular ones at the coners. Inside the fortress, the rooms on the ground floor and part of the first floor house the new “Museum of the Castle of Santa Severa”, which tells the story and archaeology of the complex and its settlement, from the martyrdom of Santa Severa in 1615 to the 20th century. The phases in which the castle was owned by the abbeys of Farfa and the monastery of San Paolo fuori le mura are also illustrated, and the period in which the noble Roman families between the 13th and 14th centuries were owners of the castle. The story continues in the Renaissance period and in the 17th century with the frequent visits of the popes to the castle and with the arrival, in 1615, of Hasekura Tsunenaga, the first Japanese ambassador to Italy, to conclude with an interesting series of images of the place in the 19th and 20th centuries. Don't miss looking out from the most suggestive window of the Rocca, which opens onto the coast, in whose space a lively decoration is preserved with the seventeenth-century coat of arms of the tutor Cesare Racagni. You can conclude the visit by going up to the top floor where you have the possibility of using the bridge to access the Saracen Tower.