catacomb vs reliquary

catacomb

noun
  • An underground system of tunnels and chambers with recesses for graves, used (in former times) as a cemetery; a tunnel system used for burying the dead, as in Paris or Ancient Rome. 

reliquary

noun
  • A container to hold or display religious relics. 

  • A person who owes a balance. 

  • An object that sustains the memory of past people or events. 

How often have the words catacomb and reliquary occurred in a corpus of books? (source: Google Ngram Viewer )