This is Trajan's Column, to celebrate his conquest of the Dacians. And that statue at the top? Trajan of course? No! It's St. Peter. Not only didn't he conquer the Dacians I bet he never even saw a Dacian.
Just around the corner is the Pantheon, a huge dome built by the Romans to house shrines to the seven major gods of their religion, who the planets in our solar system were named after. You'd think there'd be a nice statue of Mercury in there, perhaps one of Jupiter. Nope, more mooochers moved in and the current tenants are Mary and all the Martyr Saints.
I tell you this has become a bad neighbourhood since all these out of towners have shown up.