public square vs quadrangle

public square

noun
  • Synonym of town square 

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 public square and quadrangle occurred in a corpus of books? (source: Google Ngram Viewer )