landmark

noun

1. 1

   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

2. 2

   a mark showing the boundary of a piece of land

3. 3

   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

4. 4

   the position of a prominent or well-known object in a particular landscape

   the church steeple provided a convenient landmark