First proposed in legislation passed in 1859, Prospect Park was laid out by Frederick Law Olmsted and Calvert Vaux, who also helped design Manhattan's Central Park, following various changes to its design. Prospect Park opened in 1867, though it was not substantially complete until 1873. The park subsequently underwent numerous modifications and expansions to its facilities. Several additions to the park were completed in the 1890s, in the City Beautiful architectural movement. In the early 20th century, New York City Department of Parks and Recreation (NYC Parks) commissioner Robert Moses started a program to clean up Prospect Park. A period of decline in the late 20th century spurred the creation of the Prospect Park Alliance, which refurbished many parts of the park starting in the late 1980s.