Oh, Peter's been found: here's a pretty good
account of what you'll see and hear if you go to see the
scavi (excavations) under St. Peters, built over Constantine's original basilica, built over a cemetery, on top of a monument, over the catacomb in which was the sarcophagus containing the bones was found... (yes, layer upon layer, century on century, so that going down through layers of masonry rubble is like going backward in time)...fascinating.