curtain vs superstructure

curtain

noun
  • That part of a wall of a building which is between two pavilions, towers, etc. 

  • Death. 

  • A piece of cloth covering a window, bed, etc. to offer privacy and keep out light. 

  • A similar piece of cloth that separates the audience and the stage in a theater. 

  • The beginning of a show; the moment the curtain rises. 

  • The flat area of wall which connects two bastions or towers; the main area of a fortified wall. 

verb
  • To hide, cover or separate as if by a curtain. 

  • To cover (a window) with a curtain; to hang curtains. 

superstructure

noun
  • All that part of a building above the basement. 

  • The sleepers and fastenings, in distinction from the roadbed. 

  • The social sphere of ideology which includes religion, art, politics, law and all traditional values. 

  • Any material structure or edifice built on something else; that which is raised on a foundation or basis. 

  • Any structure built above the top full deck (FM 55-501). 

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