henge vs memorial

henge

noun
  • A prehistoric enclosure in the form of a circle or circular arc defined by a raised circular bank and a circular ditch usually running inside the bank, with one or more entrances leading into the enclosed open space. 

memorial

noun
  • Something, such as a monument, by which someone or something is remembered. 

  • A chronicle or memoir. 

  • A service of remembrance or commemoration. 

  • A statement of facts set out in the form of a petition to a person in authority, a court or tribunal, a government, etc. 

adj
  • Serving as a remembrance of someone or something; commemorative. 

  • Contained in the memory. 

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