The Washington Monument is an obelisk on the National Mall in Washington, D.C., built to commemorate George Washington, once commander-in-chief of the Continental Army and the first President of the United States. Located almost due east of the Reflecting Pool and the Lincoln Memorial, the monument, made of marble, granite, and bluestone gneiss, is both the world's tallest predominantly stone structure and the world's tallest obelisk, standing 554 feet 7 11⁄32 inches (169.046 m) tall according to the U.S. National Geodetic Survey (measured 2013–14) or 555 feet 5 1⁄8 inches (169.294 m) tall according to the National Park Service (measured 1884). It is the tallest monumental column in the world if all are measured above their pedestrian entrances; Progress toward a memorial finally began in 1833. That year a large group of citizens formed the Washington National Monument Society. In 1836, after they had raised $28,000 in donations (equivalent to $1,000,000 in 2018), they announced a competition for the design of the memorial; The society held a competition for designs in 1836. In 1845, the winner was announced to be architect Robert Mills; Construction of the monument began in 1848 with the excavation of the site, the laying of the cornerstone on the prepared bed, and laying the original foundation around and on top of the cornerstone, before the construction of its massive walls began the next year; Even though unpaid slave labor is not explicitly mentioned by Louis Torres or any other source, it would have been needed to augment the small paid labor force of skilled and unskilled workers totaling; Construction continued until 1854, when donations ran out and the monument had reached a height of 152 feet (46.3 m). At that time a memorial stone that was contributed by Pope Pius IX, called the Pope's Stone, was destroyed by members of the anti-Catholic, nativist American Party, better known as the "Know-Nothings", during the early morning hours of March 6, 1854 (a priest replaced it in 1982 using the Latin phrase "A Roma Americae" instead of the original stone's English phrase "Rome to America"). This caused public contributions to the Washington National Monument Society to cease, so they appealed to Congress for money; The Civil War halted all work on the monument, but interest grew after the war's end. Engineers studied the foundation several times to determine if it was strong enough. In 1876, the Centennial of the Declaration of Independence, Congress agreed to appropriate another $200,000 to resume construction; Construction resumed in 1879 under the direction of Lieutenant Colonel Thomas Lincoln Casey of the United States Army Corps of Engineers; The Monument was dedicated on February 21, 1885; At completion, it was the tallest building in the world, until the Eiffel Tower was completed in 1889. It is the tallest building in Washington, D.C.;