The Vatican’s Facebook page notes:
Pope Francis’ medallion portrait has just been added yesterday to the series of mosaic medallions depicting all the Popes throughout history, situated around the transept and nave of the Roman Basilica of St. Paul Outside-the-Walls.
Read more about the basilica’s history here.
St. Paul’s is today the only one of Rome’s four major papal basilicas entrusted to the care of a religious order. Benedictine monks have resided there since the time of Pope Gregory I (590-604), who was himself a former monk, and one of the legacies of that tradition is the basilica’s extensive library, whose collection includes some 10,000 volumes dating from before the 18th century.
The dynamic evangelizing spirit of its patron saint made the basilica a fitting site for the January 25, 1959, announcement by Blessed John XXIII that he would call an ecumenical council known to history as Vatican II.
The basilica’s current role as a center of ecumenism draws inspiration from St. Paul, who did so much to bind the early church together. A chapel is set aside for worship by non-Catholic Christians, and the pope leads an ecumenical service in the basilica every year at the end of the Week of Prayer for Christian Unity.
St. Paul’s stands as a monument to that hoped-for unity, since the basilica was destroyed by fire in 1823, then rebuilt with contributions from Catholics and others around the world, including the Orthodox Tsar Nicholas I of Russia, who gave blocks of malachite and lapis lazuli. Help also came from non-Christians, notably Muhammad Ali, viceroy of Egypt, who donated alabaster columns.
For pilgrims and other visitors today, one of the basilica’s most noteworthy features is the series of mosaic medallion portraits of all the popes… A popular legend holds that the apocalypse will come once the number of popes exhausts the available spaces for portraits. Yet the story of the basilica’s rebuilding is a reminder that the Catholic Church’s power of endurance and growth is greater than any physical construction.