a prominent or conspicuous object on land that serves as a guide, especially to ships at sea or to travelers on a road; a distinguishing landscape feature marking a site or location:
The post office served as a landmark for locating the street to turn down.
something used to mark the boundary of land.
a building or other place that is of outstanding historical, aesthetic, or cultural importance, often declared as such and given a special status (landmark designation) ordaining its preservation, by some authorizing organization.
a significant or historic event, juncture, achievement, etc.:
The court decision stands as a landmark in constitutional law.
O.E. landmearc, from land (n.) + mearc (see mark). Originally "object set up to mark the boundaries of a kingdom, estate, etc." Modern figurative sense of "event, etc., considered a high point in history" is from 1859.