Suburbicarian diocese

The six suburbicarian dioceses are Roman Catholic dioceses located in the suburbs that surround Rome. A Cardinal is named titular bishop of each of the six sees (which have varied slightly in history but are now Velletri-Segni, Porto-Santa Rufina, Frascati, Palestrina, Albano, and Sabina-Poggio Mirteto) and the see of Ostia is additionally conferred on the Dean of the College, who is chosen by and from among the six cardinal bishops (formerly it was always the longest-serving cardinal bishop). However, since the 1960s each of the six dioceses has had its own substantive bishop, pursuant to a decree of Pope John XXIII titled Suburbicarii Sedis. Ostia is administered by the Cardinal Vicar-General of Rome. The titular bishops still formally "take possession" of the dioceses but the substantive bishops exercise all ordinary jurisdiction.