A group of buildings in Rome, clustered around the palace of the Pope. The first to build a residence near the ancient Basilica of St. Peter was Pope Summachus (reigned 498-514). Through subsequent purchase the popes acquired possession of the entire Vatican Hill. The property now is the largest palace in the world. Only a small part is used for living quarters; most of the buildings serve the purpose of the arts and sciences, and the administration of Church affairs.