The Mount Rushmore National Memorial is a sculpture carved into the granite face of Mount Rushmore near Keystone, South Dakota, in the United States. Sculpted by Danish-American Gutzon Borglum and his son, Lincoln Borglum, Mount Rushmore features 60-foot (18 m) sculptures of the heads of four United States presidents: George Washington (1732–1799), Thomas Jefferson (1743–1826), Theodore Roosevelt (1858–1919) and Abraham Lincoln (1809–1865). The entire memorial covers 1,278.45 acres (5.17 km2) and is 5,725 feet (1,745 m) above sea level.
The ongoing conservation of the site is overseen by the US National Park Service. Physical efforts to conserve the monument have included replacement of the sealant applied originally by Gutzon Borglum, which had proved ineffective at providing water resistance (components include linseed oil, granite dust and white lead). A modern silicone replacement was used, disguised with granite dust.