Palazzo dei Papi (Palace of the Popes) in Viterbo, Italy

Viterbo, Italy, is known as the "City of the Popes" due to its historical connection with the papacy. The city's Palazzo dei Papi, a Gothic-style palace, was the residence of the pope during a period in the 13th century. The papacy moved to Viterbo for 24 years after the commune of Rome turned against the pope due to opposition to his interference in secular affairs. The bishops' palace was upgraded to accommodate the pope, but the construction work was not always of high quality, as evidenced by the collapse of the roof of Pope John XXI's study in 1277. The Sala de Conclave in the palace is notable for being the site of the first and longest papal election conclave in history, which lasted 33 months. The people of Viterbo resorted to isolating the cardinals and reducing their food supply to force a decision. The Cathedral of Viterbo, also known as the Duomo, is adjacent to the palace and houses many papal treasures in the Colle de Duomo Museum. Although the papacy returned to Rome, Viterbo continued to be used as a luxurious retreat by the popes. Nicholas V, in particular, was fond of the city's luxuries and commissioned a "bath palace" to make use of the thermal springs in the area. The city's history and architecture reflect its significant connection to the papacy.