Definitions for "National Historic Landmark"
a program providing official federal recognition of nationally-significant properties. This program is administered by the National Register of Historic Places.
National Historic Landmarks "possess exceptional value or quality in illustrating and interpreting the heritage of the United States." This is a national designation and only a small fraction of all sites listed in the National Register of Historic Places bear this designation. The City of Buffalo contains a number of National Historic Landmarks, including the Darwin D. Martin House, Kleinhans Music Hall, Buffalo State Hospital, the Buffalo and Erie County Historical Society Building, the Prudential Building, and St. Paul's Cathedral. In Niagara Falls, New York, the Adams Power Plant Transformer House and the Niagara Reservation are similarly recognized as National Historic Landmarks. For more information about this designation, including a database containing all National Historic Landmarks, see the National Historic Landmarks Program
(NHL) -- buildings, historic districts, structures, sites, landscapes, and objects that possess exceptional values or quality in illustrating or interpreting the heritage of the United States. The NHL program is run by the National Park Service, U.S. Department of the Interior.