The story was that the original church was built by Emperor Constantine on top of Peter’s tomb. When the basilica was built about a thousand years later. Peter’s bones were moved to its current location a few hundred yards away.
This video gives a glimpse of the jeweled box and Peter’s bones. https://youtu.be/DhnJgAzSHD8
https://www.youtube.com/watch?v=JwDqKWMLSIM
A detailed and lengthy explanation of the necropolis, excavations, and findings is available here:
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Australia FWIW