The Washington Monument is the world's tallest predominantly stone structure and the world's tallest obelisk, standing 554 feet 7 11⁄32 inches (169.046 m). Located in Washington, D.C, the structure commemorates President George Washington. It is made of marble, granite, and bluestone gneiss. Although it stands as a proud symbol to this day, there had been many trials that followed the obelisk's construction and maintenance. Work started in 1848 and it is argued that it was very likely that African-American slaves were among the construction workers. As donations ran out, the construction was halted in 1854, leaving the obelisk at 152 feet (46.3 m). After the Civil War ended and endless political and financial struggles ensued, the construction resumed in 1879 and the obelisk was finally finished on October 9, 1888.