pantheon vs sacellum

pantheon

noun
  • A temple dedicated to all the gods. 

  • All the gods of a particular people or religion, particularly the ancient Greek gods residing on Olympus, considered as a group. 

  • A category or classification denoting the most honored persons of a group. 

sacellum

noun
  • A small chapel, as a monument within a church. 

  • In Ancient Rome, a shrine open to the sky, sometimes used for sacrificial purposes, or in honor of the divine. 

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