colonnade vs piazza

colonnade

noun
  • A portico or stoa. 

  • A peristyle. 

  • A series of columns at regular intervals. 

  • A regular row of anything, such as trees. 

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