The edifice constitutes the biggest gothic palace in the world —a surface area of 15,000 m2, or the equivalent of 4 gothic cathedrals. The Palace construction began in 1252 and became the Papal residence in 1309. The immediate reason for the erection of the Papal Residence was the removal of the Curia from Rome to Avignon. Indeed by 1309, Rome became a violent and unwelcoming city and it became impossible for the incimbent Pope -Pope Clement V- to remain in the city. As a result the Pope and his entourage relocated to Avignon. One time fortress and palace, the papal residence was the seat of Christianity during the 14th century and made the city a major political capital of the western world. Six papal conclaves were held in the Palace, leading to the elections of Benedict XII in 1334, Clement VI in 1342, Innocent VI in 1352, Urban V in 1362, Gregory XI in 1370 and Antipope Benedict XIII in 1394. At the end of the 14th century, the popes departed Avignon, returning to Rome. The building remained in the hands of papal forces until the French Revolution and it is now a museum and an exhibition centre.