bird's-eye view vs observatory

bird's-eye view

noun
  • The view from directly or high above. 

  • A general overview or summary of a topic. 

observatory

noun
  • A lookout (vantage point with a view of the surrounding area) 

  • A place where stars, planets and other celestial bodies are observed, usually through a telescope; also place for observing meteorological or other natural phenomena. 

How often have the words bird's-eye view and observatory occurred in a corpus of books? (source: Google Ngram Viewer )