(CNN) -- Here's some background information about the Mount Rushmore National Memorial, composed of sculptures of the faces of former Presidents George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt.
Facts: The monument is located on Mount Rushmore in the Black Hills of South Dakota.
It stands 5,725 feet above sea level.
It cost $989,992.32 to build.
More than two million tourists visit each year. In 2013, 2,162,998 people visited the monument.
Timeline: 1923 - The idea is suggested by Jonah "Doane" Robinson, secretary of the South Dakota State Historical Society.
October 1, 1925 - Mount Rushmore is dedicated as a national monument.
October 4, 1927 - Work begins on the monument. The sculptor/designer is Gutzon Borglum. Four hundred workers sculpt the monument using dynamite and drills. Workers use much smaller models (about one-twelfth the size) to envision the final product.
July 4, 1930 - The section of George Washington is dedicated.
June 10, 1933 - FDR issues Executive Order 6166 making Mount Rushmore part of the National Park Service.
August 30, 1936 - Thomas Jefferson's section is dedicated.
September 17, 1937 - Abraham Lincoln's section is dedicated.
July 2, 1939 - The Theodore Roosevelt section is dedicated.
March 6, 1941 - Borglum dies. His son, Lincoln, completes work on Mount Rushmore.
October 31, 1941 - Drilling on the monument is complete. It only takes six and a half years of actual work on the monument, but the Great Depression slowed down its completion due to lack of federal funds.