What would I see on one? I googled got that crypt and the dig part...

you will see a pagan and early christian cemetary- very interesting - within which it is believed the remains of St. Peter were secreted, hear a fascinating account of the ground under St. Peters and the building and excavation history and then finally, amazingly you will see a small container with bones that are thought to be those of the saint. Its a holy place - the tour will be led by a priest. Its more the story and the fact of the place - what it represents and the truth of the story that can be demonstrated more than any touristic SIGHTS that makes it very special. If you are not interested in archeology, ancient or christian history or the christian faith, or would have a problem with being respectful during a prayer at the end, its not the place for you.

Thank you. I was thrilled to be in the archeological crypt that is underneath the plaza a wee west of Notre Dame. I could be respectful.

Our Scavi tour under St. Peter's was not lead by a priest and there was no prayer at the end. Extremely intereting and well worth it anyway.

Our tour was lead by a nun (a very funny and informative nun, I might add). There was no prayer at the beginning, middle or end of the tour.

Our group loved the tour.

Our tour included a priest who was asked to say a prayer at the end. I'm not religious but managed to remember all the words to the Lord's Prayer (which we had to recite every morning at school until I was about 10)--

Our guide was rather young and Russian (and excellent).
At the end he said people could remain behind to say a prayer if they wished. No prayer was done for all of us.

By the way, I'm curious what part of your question did you think was stupid? I didn't see that part.

I was being humble <GRIN> or obsequious. And trying not to be offensive. I didn't know what the thing was and yet all the travellers seem to. I suppose the tour wasn't available when I was in the Vatican.
I remember watching the some guy on a platform painting the ceiling though (it was that long ago!).