Mount Rushmore National Memorial, near Keystone, South Dakota, is a monumental granite sculpture located within the United States Presidential Memorial that represents the first 150 years of the history of the United States of America with 60-foot (18 m) sculptures of the heads of former United States presidents: George Washington (1732-1799), Thomas Jefferson (1743-1826), Theodore Roosevelt (1858-1919), and Abraham Lincoln (1809-1865).^[1] The entire memorial covers 1,278 acres (5.17 km²),^[2] and is 5,725 feet (1,745 m) above sea level.^[3] It is managed by the National Park Service, a bureau of the United States Department of the Interior. The memorial attracts approximately 2 million people annually.^{[4]
http://en.wikipedia.org/wiki/Mount_Rushmore}