The Papal Palace of Castel Gandolfo, or the Apostolic Palace of Castel Gandolfo from its Italian name Palazzo Apostolico di Castel Gandolfo, is a 17th-century papal palace in the city of Castel Gandolfo, Italy. It has served for centuries as a summer residence and vacation retreat for the pope, the leader of the Catholic Church. Although situated within Castel Gandolfo, the residence is afforded extraterritorial status as one of the properties of the Holy See and is not under the jurisdiction of Castel Gandolfo or Italy.HistoryThe gardens occupy the site of a residence of the Roman Emperor Domitian. The palace was designed by Swiss-Italian architect Carlo Maderno for Pope Urban VIII. Popes have used the properties as a summer residence and vacation retreat, except for the years between 1870 and 1929 when the popes, in dispute with Italy over territorial claims, did not leave Vatican City. Pope Pius XI had the facilities modernized and began using the retreat again in 1934. In accordance with the Lateran Treaty of 1929, the palace and the adjoining Villa Barberini added to the complex by Pope Pius XI are extraterritorial properties of the Holy See.During World War II, an unknown number of Jewish refugees took shelter at the palace under the protection of the Holy See and many people used the site as a refuge from Allied bombing raids in 1944, though more than 500 people died in one such attack.