old town vs plaza

old town

noun
  • The historic district of a city or town. 

  • Used other than figuratively or idiomatically: see old, town. 

plaza

noun
  • A town's public square. 

  • A shopping mall. 

  • A strip mall. 

  • An open area used for gathering in a city, often having small trees and sitting benches. 

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