Today marks the anniversary of the dedication of the cathedral church of Rome on land owned by the Laterani family by Pope St. Sylvester I (31 Dec.), 9 Nov. 324; honored as the episcopal seat of the pope as bishop of Rome; according to an inscription which Pope Clement XII (reigned 1730-1740) placed on the façade, this basilica is the "mother and head of all churches of Rome and the world" ("omnium ecclesiarum Urbis et Orbis mater et caput"); residence of the popes from the 4th c. until their moving to Avignon (1309); site of five ecumenical councils; Pope Innocent X commissioned the present structure in 1646; beneath its high altar rests the remains of the small wooden table on which, according to tradition, St. Peter celebrated Mass; dedicated to the Savior, later to St. John the Baptist.