Gregory XV issued two bulls that covered the most minute of details relating to the election; the first, in 1621, concerned electoral processes, while the other, in 1622, fixed the ceremonies to be observed. In December 1904 Pope Pius X issued an apostolic constitution consolidating almost all the previous rules, making some changes, Vacante sede apostolica. John Paul II instituted several reforms in 1996. The location of the conclaves became fixed in the fourteenth century. Since the end of the Western Schism in 1417, they have taken place in Rome (except in 1799–1800, when French troops occupying Rome forced the election to be held in Venice), and normally in what, since the Lateran Treaties of 1929, has become the independent Vatican City State. Since 1846, when the Quirinal Palace was used, the Sistine Chapel in the Vatican has served as the location of the election. Popes have often fine-tuned the rules for the election of their successors: Pope Pius XII's Vacantis Apostolicae Sedis (1945) governed the conclave of 1958, Pope John XXIII's Summi Pontificis electio (1962) that of 1963, Pope Paul VI's Romano Pontifici eligendo (1975) the two conclaves of 1978, John Paul II's Universi Dominici Gregis (1996) that of 2005, and two amendments by Benedict XVI (2007, 2013) that of 2013. Modern practice In 1996, John Paul II promulgated a new apostolic constitution, Universi Dominici gregis, which with slight modifications by Pope Benedict XVI now governs the election of the pope, abolishing all previous constitutions on the matter, but preserving many procedures that date to much earlier times. Under Universi Dominici gregis, the cardinals are to be lodged in a purpose-built edifice in Vatican City, the Domus Sanctae Marthae, but are to continue to vote in the Sistine Chapel. Several duties are performed by the dean of the College of Cardinals, who is always a cardinal bishop. If the dean is not entitled to participate in the conclave owing to age, his place is taken by the vice-dean, who is also always a cardinal bishop. If the vice-dean also cannot participate, the senior cardinal bishop participating performs the functions. Since the College of Cardinals is a small body, there have been proposals that the electorate should be expanded. Proposed reforms include a plan to replace the College of Cardinals as the electoral body with the Synod of Bishops, which includes many more members. Under present procedure, the synod may