museum piece vs relic

museum piece

noun
  • A very old item, especially an obsolete piece of technology. 

relic

noun
  • Something old and outdated, possibly kept for sentimental reasons. 

  • A part of the body of a saint, or an ancient religious object, kept for veneration. 

  • That which remains; that which is left after loss or decay; a remaining portion. 

verb
  • To cause (an object) to appear old or worn, to distress. 

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