St Peter's Basilica is the largest church in christendom but has been designed to detract from the size so as not to appear intimidating. As an example of just how big it is - this sculpture is the largest bronze sculpture in the world. If it was raised up the whole thing would fit snugly into the little inset in the dome, above. The following picture shows me filling the little bottles I bought (under the counter!) from the nuns, with holy water that the pope kindly blessed for me. It leaked a little in my suitcase on the way home.