Borough vs Tower

Borough

name
  • The area, properly called Southwark, just south of London Bridge, which is at the north end of Borough High Street (OS grid ref TQ3279). 

Tower

name
  • The Tower of London, especially seen as a place of imprisonment or punishment. 

  • A habitational surname.; Alternative form of Towers 

noun
  • Denoting the system of weights used by the Saxon and Norman English kings in their minting of coins. 

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