What is a Landmark Building?

The Evergreen Building by Arthur Erickson, 1285 West Pender Street, Vancouver
Some other useful definitions:
From Wikipedia:
Originally, a landmark literally meant a geographic feature used by explorers and others to find their way back or through an area.
en.wikipedia.org/wiki/Landmark_building
From Vancouver.ca
When the Heritage Register was initially conceived it only included buildings that were constructed before 1940. However, the post-war era in Vancouver produced an important collection of buildings with local, regional and national significance noted for their innovative design, technological features and social significance. The Recent Landmarks Program was initiated to identify the most important buildings from this period. Recent Landmark buildings, that are at least 20 years old and meet the same evaluation criteria for Register properties, can be considered for inclusion in the Register. A list of 100 buildings was identified for possible inclusion in the Heritage Register. To date, 22 of these buildings have been added to the Register. Five of these are also protected through designation: the former BC Hydro building, the former Vancouver Public Library, the Gardner House in Southlands, and the Dodek House in Oakridge, and the Evergreen Building.
http://vancouver.ca/commsvcs/planning/heritage/Fact2.htm
View the Vancouver Heritage register here