observation post vs vista

observation post

noun
  • a lookout or vantage point 

vista

noun
  • A distant view or prospect, especially one seen through some opening, avenue or passage. 

  • A vision; a view presented to the mind in prospect or in retrospect by the imagination. 

  • A site offering such a view. 

verb
  • To make a vista or landscape of. 

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