A series of 265 circular mosaic portraits that depict every pope since St. Peter are mounted in a continuous line on the frieze that runs above the columns and below the nave windows of the Basilica di San Paolo in Rome.  Only the image of the current pope is illuminated, but visible just beyond that are a handful of vacant spots.  The story goes that once they, too, have been filled, the world will come to an end.

Little-Known Facts About Well-Known Places: Italy