Peter...or whom ever, whoever Jesus said the rock thing to was the first Pope,it was to Peter and the words was You are the rock and upon this rock I will build my church; and the gates of hell(hades) shall not prevail against it .
Peter is regarded by many as the first Pope because he was said to be the bishop of Rome. A lot of people discuss back and forth whether Peter ever was in Rome at all. It is also said that Peter was crucified upside down and buried at Vatican Hill.
Others claim that James the just(Jesus brother to be the head of the church in its earlier days.
Dont you just love it when followers of chrisitanity doesnt agree on anything at all