peanut gallery vs piazza

peanut gallery

noun
  • In the nineteenth century, the cheap seats at the back of a theatre or in the upper balcony. 

  • Any source of heckling, unwelcome commentary or criticism, especially from a know-it-all or of an inexpert nature. May also now refer to general audience response: "Let's hear it from the peanut gallery." 

  • The upper balcony to which black patrons were restricted in racially segregated venues such as theatres. 

piazza

noun
  • A roofed gallery or arcade (for example around a public square or in front of a building). 

  • A public square, especially in Italian cities. 

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