Where is anybody's tomb?
Absence of evidence is not evidence of absence.
Even if someone claims to know where Mary's tomb was, or even the tomb in which Jesus was laid, there's simply no way of knowing for sure.
Any evidence is based on hearsay and could have been fabricated at any point in the last couple THOUSAND years.
It is to CATHOLICS!!!
As long as someone in AUTHORITY has made the claim; who are they; a mere pew warmer; to challenge it?