Washington DC
circa 1960

The Washington Monument is an obelisk-shaped building, on the National Mall in Washington, D.C., built to commemorate George Washington, commander-in-chief of the Continental Army in the American Revolutionary War and the first President of the United States.
Standing 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 measurements by the U.S. Geodetic Survey in 2013–2014 or 555 feet 5+1⁄8 inches (169.294 m) tall, according to the National Park Service's 1884 measurements. It is the tallest monumental column in the world if all are measured above their pedestrian entrances. It was the tallest structure in the world between 1884 and 1889, after which it was overtaken by the Eiffel Tower, in Paris. Previously, the tallest structure was the Cologne Cathedral.

Construction of the presidential memorial began in 1848; it was halted from 1854 to 1877 by lack of funds, a struggle for control over the Washington National Monument Society, and the American Civil War. Although the stone structure was completed in 1884, internal ironwork, the knoll, and installation of memorial stones were not completed until 1888. A difference in shading of the marble, visible about 150 feet (46 m) or 27% up, shows where construction was halted and later resumed with marble from a different source. The original design was by Robert Mills (1781–1855), of South Carolina; but construction omitted his proposed colonnade, for lack of funds, proceeding only with a bare obelisk. The cornerstone was laid on July 4, 1848; the first stone was laid atop the unfinished stump on August 7, 1880; the capstone was set on December 6, 1884; the completed monument was dedicated on February 21, 1885; and officially opened October 9, 1888.