belvedere vs observatory

belvedere

noun
  • A turret or other raised structure offering a pleasant view of the surrounding area. 

  • Bassia scoparia (summer cypress) 

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 belvedere and observatory occurred in a corpus of books? (source: Google Ngram Viewer )