city center vs metropolitan

city center

noun
  • The central business and shopping area of a city. 

metropolitan

noun
  • The inhabitant of a metropolis. 

  • A bishop empowered to oversee other bishops; an archbishop. 

adj
  • Of or pertaining to the parent state of a colony or territory, or the home country, e.g. metropolitan France 

  • Pertaining to the see or province of a metropolitan. 

  • Of, or pertaining to, a metropolis or other large urban settlement. 

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