flea market vs piazza

flea market

noun
  • An outdoor temporary market selling inexpensive antiques, curios etc. 

  • A permanent indoor market of stalls in a warehouse selling inexpensive antiques, outdated goods, curios, etc. 

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 flea market and piazza occurred in a corpus of books? (source: Google Ngram Viewer )