piazza vs quadrangle

piazza

noun
  • A public square, especially in Italian cities. 

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

quadrangle

noun
  • The buildings forming the border of such a courtyard. 

  • A geometric shape with four angles and four straight sides; a four-sided polygon. 

  • A courtyard which is quadrangular. 

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