The Castle of Santa Severa was founded around the year one thousand when the Tuscia counts built a fortress dedicated to the young Severa, martyred nearby between 284 and 305 A.D. The current castle was built, however, from the fourteenth century and the nearby village formed in the following two centuries. From 1500 it belonged to the Order of the Holy Spirit and for a couple of centuries had been a stopping place and residence of many popes, among them Gregory XIII, Sixtus V and Urban VIII. In 1943 it was used by the Germans as a strategic military post. Today the castle belongs to the municipality and houses permanent collections and exhibitions.