One of the many statues in the Vatican museum
I would estimate that you could take 5 St. Patrick's cathedrals and put them inside St. Peter's. It's a bit absurd how big this place is. No church in the world is allowed to be bigger than this one. It's the law! If you want to know where that dollar you drop into the basket goes every Sunday. Here it is.
They say the pope's room is out there on the upper right.