Before they were banished to the Vatican in the early 20th century, popes were the political as well as religious leaders of Rome. As a result, the city is chock full of past pontiffs. Every church of any stature has at least one buried there. We got to the point where we started rating churches by number of popes (“that’s a three-Poper”). The big, grand basilica of Santa Maria Maggiore near the train station is (if we counted rightly) a seven-Poper!
It was obviously important for popes to advertise themselves. Not just churches but bridges, gateways, fountains, and even ancient Roman sites (such as the Colosseum, the Pantheon, and the baths of Emperor Diocletian) have stone plaques on them dedicated to some Pope or other. Can’t you picture legions of papal assistants combing the city for some unclaimed monument that their guy can slap a plaque on, like European kings claiming continents?
We didn’t have to content ourselves only with papal plaques. On display in St. Peter’s is the body of Pope Paul the 23rd, who died a few decades ago. Apparently, after a pope passes away, functionaries routinely check on the state of his body to see how it’s decomposing. If it’s in unusually good shape, the authorities pay special attention to it: There’s a chance that said pope may prove “incorruptible,” which is one indication of sainthood. It’s too early to tell with Paul the 23rd, but the pilgrims in St. Peter’s file by his glass coffin for a look just in case.