This was done by Pope Gregory XI upon his return from Avignon. Vatican Hill became the seat of the pope, the Roman Curia, and the center of the entire Roman Catholic Church. Successive popes carried out their construction projects there: churches, chapels, administrative buildings, fortifications, accommodations, and more.
In 1506 the construction of St. Peter’s Basilica began, and in 1589 Pope Sixtus V commissioned the construction of the Apostolic Palace, which is still the residence of the Pope and important administrative bodies. This situation persisted until 1870 when King Victor Emmanuel II of Italy incorporated the existing Church State on Vatican Hill into the Kingdom of Italy. The Pope did not come to terms with this decision and declared himself a prisoner of the Vatican. It was not until 1929 that Benito Mussolini’s fascist government and the Holy See signed the so-called Lateral Treaties, which guaranteed the existence of the Vatican State within the Apostolic Palace and Vatican Gardens.
