Papal Palace of Castel Gandolfo

The papacy came into Castel Gandolfo through a debt. The castle was acquired in July 1596 by the Apostolic Camera, in payment of money owed by the Savelli family, and on 27 May 1604 the territory was incorporated as inalienable patrimony of the Holy See. The castle itself dated from the thirteenth century, and fragments of medieval frescoes from the old stronghold of the Gandolfi and the Savelli survive inside the later building. The gardens occupy the site of a residence of the Roman emperor Domitian, thought in turn to have risen on the acropolis of ancient Alba Longa.

Urban VIII, elected in 1623, began building on the site almost at once. The design of the palace, called at the time the suburban retreat, went to the Swiss-Italian architect Carlo Maderno, who carried it out with his assistants Bartolomeo Breccioli and Domenico Castelli, the work dated to 1629. Whether the pope who commissioned it ever lived there is told two ways. By one account Urban VIII began using the palace in the spring of 1626; by another he never lived in it at all, preferring the neighbouring Villa Barberini, which belonged to his nephew Taddeo Barberini.

On that second account the first pope to summer in the palace was the Sienese Alexander VII, who completed it with the principal facade and the western wing, a work to which Gian Lorenzo Bernini also contributed. Of the popes reigning since, about half have used the properties as a summer residence and holiday retreat.

The villa was then left largely alone for about a century. It came back into use in the eighteenth century under Benedict XIV, who restructured it with alterations and new decoration. Clement XIV did as much again, and in 1773 bought the adjoining Villa Cybo, enlarging Urban VIII's original garden into a park. The palace was afterwards occupied and severely damaged by Napoleonic troops, and restored by Pius VII and Pius VIII.

Gregory XVI made particular use of the palace as a summer residence, and Pius IX after him, at least until 1870; both made further improvements to it. From 1870, with the end of the Papal States, the popes abandoned Castel Gandolfo along with every other residence they held outside Rome, shutting themselves inside the Vatican in open protest against the Italian state. Between 1870 and 1929, in dispute with Italy over territorial claims, they did not leave Vatican City at all. The extraterritoriality of the Pontifical Villas had already been granted to the Holy See by the Law of Guarantees in 1871, along with the basilica and palace of the Lateran in Rome.

The Lateran Treaty of 1929, which accompanied the birth of the Vatican City State, reconfirmed that status. The papal villas, to which the neighbouring Villa Barberini was now added, remained legally Italian territory but were declared extraterritorial papal domain, with a standing comparable to that of diplomatic missions. They are exempt from Italian taxes and expropriations, and Italian authorities are forbidden to enter without the consent of the Holy See. The complex is also designated Italian national heritage.

It was with Pius XI that the Apostolic Palace returned to being the popes' summer residence. He had the facilities modernised and began using the retreat again in 1934, and commissioned the architect Giuseppe Momo to join the three adjoining properties that the public roads divided: a loggia linking the Apostolic Palace to Villa Cybo, and an overpass connecting the garden of the latter with that of Villa Barberini. In the same year he had the Vatican astronomical observatory, the Specola Vaticana, installed on the palace's top floor beneath the tower. Further land bought towards Albano Laziale allowed a small farm, so that the papal holdings now form a single park of about fifty-five hectares, greater in extent than the Vatican state itself.

During the Second World War 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 five hundred died in one such attack. The palace afterwards saw the deaths of two popes: Pius XII died there in 1958, and Paul VI in 1978.

The popes went on using it in their periods of rest, so much so that John Paul II called Castel Gandolfo the "Vaticano Due"; on those stays the Sunday Angelus was recited inside the courtyard. He had a swimming pool built at the palace, which some criticised, and paparazzi took the opportunity to photograph him. In 2010, under Benedict XVI, a general audience was held in the piazza outside the palace for the first time, and the practice continued through the two following years.

Benedict XVI flew to the palace at the conclusion of his papacy on 28 February 2013, was joined by Pope Francis for lunch on 23 March and returned to Vatican City on 2 May; in retirement he came back for a fortnight in July 2015 at Francis's invitation. Francis visited twice more but never stayed overnight, and in June 2013 announced that he would not spend the summer at Castel Gandolfo as many of his predecessors had, though he would lead the Angelus there on 14 July. On 7 December 2013 he named Osvaldo Gianoli Director of the Pontifical Villas. In March 2014 the Barberini Gardens were opened to paying visitors on escorted morning tours, and from 11 September 2015 the public could travel from Vatican City to Castel Gandolfo on a train previously reserved for the pope. On 21 October 2016 Francis had the Apostolic Palace turned into a museum, opened to viewing without any structural change; asked whether it would again become a papal apartment, the mayor of Castel Gandolfo, Milvia Monachesi, said that "the fact that the palace is now a museum will make a reversal in the future difficult".

On 17 June 2025 a communique of the Prefecture of the Pontifical Household restored the palace to its status as a place of papal residency, stating that Leo XIV, elected earlier that year, would take up residence there for part of his summer holidays, from 6 to 20 July and from 15 to 17 August. He began staying at Castel Gandolfo on 6 July 2025, resuming the tradition of the town as the pope's retreat and summer home, though the main Apostolic Palace remained a museum and he lodged instead at Villa Barberini within the complex.

Minor renovations to the Papal Palace began in May 2026. Because of security problems at Villa Barberini, the Apostolic Palace was reconverted into the pope's summer residence and made habitable again for Leo XIV, who would be the sixteenth pope to spend the summer at the official summer residence of the pontiffs. He took up residence there on 5 July 2026, his stay announced to run until 27 July, and the palace served once more as a papal residence after its years as a museum.