A National Historical Landmark is a designation given by the United States government to sites that hold significant historical importance. These landmarks are recognized for their exceptional value in illustrating the heritage of the nation. They can include buildings, structures, districts, or objects that have played a crucial role in American history. To be designated as a National Historical Landmark, a site must meet specific criteria set by the National Park Service. This includes demonstrating its significance in American history, architecture, archaeology, or culture. The designation helps preserve these important sites for future generations and promotes public awareness of their historical value.