The Archbasilica of Saint John Lateran is the Catholic cathedral of the Diocese of Rome in the city of Rome, and serves as the seat of the bishop of Rome, the pope. The only "archbasilica" in the world, it lies outside of Vatican City proper, which is located approximately four kilometres northwest. Nevertheless, as properties of the Holy See, the archbasilica and its adjoining edifices enjoy an extraterritorial status from Italy, pursuant to the terms of the Lateran Treaty of 1929. Dedicated to the Christ, in honor of John the Baptist and John the Evangelist, the place name, Laterano (Lateran) comes from an ancient Roman family (gens), whose palace (domus) grounds occupied the site; the adjacent Lateran Palace was the primary residence of the pope until the Middle Ages.