Emperor Constantine was baptized on his deathbed, and thus began a transformation of Rome into a Christian (Catholic) city. At the heart of that city is the Vatican, home to an iconic work of art, Michelangelo's Pieta that has left Rome just once in its life: to go to the World's Fair in New York City in the 1960's. This is that story, told on the day when a man tried to destroy the Pieta with a geologist's hammer in St. Peter's Basilica.