Located in the heart of Velletri, surrounded by the scenic Castelli Romani, the Diocesan Museum is housed within the Cathedral’s cloister. It preserves a distinguished collection of rare and invaluable works. Its highlight is the Croce Veliterna, an 11th–12th century gold and enamel reliquary of remarkable beauty. Visitors can also admire creations by Gentile da Fabriano, Bicci di Lorenzo, Antoniazzo Romano, Rositi, and Francesco da Siena, along with noteworthy liturgical garments and ceremonial objects.