dolmen vs mirador

dolmen

noun
  • A prehistoric megalithic tomb consisting of a capstone supported by two or more upright stones, most having originally been covered with earth or smaller stones to form a barrow. 

  • More generally, any megalithic tomb, including passage graves and wedge tombs. 

mirador

noun
  • a tower that offers a panoramic view 

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