landmark

Noun

• an anatomical structure used as a point of origin in locating other anatomical structures (as in surgery) or as point from which measurements can be taken

• a mark showing the boundary of a piece of land

• an event marking a unique or important historical change of course or one on which important developments depend
  • the agreement was a watershed in the history of both nations
    

• the position of a prominent or well-known object in a particular landscape
  • the church steeple provided a convenient landmark
    

Related words

• Synonyms: 
  turning point , watershed