Within the Black Hills National Forest, visitors can view the amazing Mount Rushmore. Mount Rushmore is a memorial to the birth, growth, preservation and development of the United States of America. Between 1927 and 1941, Gutzon Borglum sculpted busts of Presidents George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln high in the Black Hills to represent the first 150 years of American history. The primary resource at Mount Rushmore is the granite sculpture itself, but also of interest is the Sculptor's Studio built under the direction of Sculptor Gutzon Borglum in 1939. Unique plaster models and tools related to the sculpting process are displayed in the studio. Recently, ten years of redevelopment work culminated with the completion of extensive new visitor facilities. These include a new Visitor Center and Museum and the Presidential Trail, a walking trail and boardwalk providing spectacular close-up views of the mountain sculpture. Other resources at the memorial include flora and fauna representative of the Black Hills environment and the unique geological formations of the mountain and adjacent peaks.