bell tower vs pylon

bell tower

noun
  • A tower in which a bell (or set of bells) is hung; a belfry. 

pylon

noun
  • A tall steel or concrete tower from which cables are strung. 

  • An orange marker designating one of the four corners of the end zone in American football. 

  • An obelisk. 

  • A traffic cone. 

  • A rigid prosthesis for the lower leg. 

  • A starting derrick for an aeroplane. 

  • A tower-like structure, usually one of a series, used to support high-voltage electricity cables. 

  • A lighting mast; a freestanding support for floodlights. 

  • A structure used to mount engines, missiles etc., to the underside of an aircraft wing or fuselage. 

  • A post, tower, etc. as on an aerodrome, or flying ground, serving to bound or mark a prescribed course of flight. 

  • A gateway to the inner part of an Ancient Egyptian temple. 

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