Santa Severa Castle, Medieval castle in Santa Marinella, Italy

Santa Severa Castle stands on the Tyrrhenian coast about 50 km northwest of Rome. Its rectangular keep has two square and two round corner towers, a battered base leaning outward against the waves, and small rectangular windows; stone brackets run beneath the projecting roofs of the towers and the long wall. A cylindrical tower, the Torre Saracena, is linked to the castle by a bridge.

The fortress was built on remains of a Roman castrum from the 3rd century BC and underwent major reconstruction in the 14th century. It later belonged to the Order of the Holy Spirit and served as a defensive post and trading center for centuries.

The village inside the walls grew in the 15th and 16th centuries under the Order of the Holy Spirit, whose patriarchal cross can still be seen there. The Church of Santa Maria Assunta, mainly built in the 16th century, is still used for worship. The castle museum, set up in 2017 in the 14th-century keep and the Saracen Tower, displays finds from the site.

The complex reopened on 24 April 2017 after restoration, managed by the regional company LAZIOcrea. It can be reached by train from Rome Termini station. The site combines the castle, the Saracen Tower, the church and museum spaces with a hostel in former village houses.

Excavations revealed a Roman residence from Imperial times and an Early Christian church dating to the 5th century beneath the castle grounds. These discoveries show the site's continuous occupation across different historical periods.