Originally, a landmark literally meant a geographicfeature, used by explorers and others to find their way back through an area on a return trip. In modern usage, it is anything that easily recognisable, such as a monument, building, or other structure.
National Historic Landmarks (NHL) are buildings, districts, sites, structures, and objects (almost always) within the United States or its insular areas and designated by the United States Secretary of the Interior because they are
Working with citizens throughout the nation, the National Historic Landmarks Program draws upon the expertise of National Park Service staff who work to nominate new landmarks and provide assistance to existing landmarks.
Following is a partial list of landmarks, with the total number of landmarks for that state or jurisdiction as of December 2004: