The actual construction of the Washington monument began when the cornerstone
was laid on July 4, 1848 but it was not completed until 1884, almost 30 years after the death of architect Robert Mills (below). This hiatus in construction was due to a lack
of funds and the intervention of the Civil War. The monument was finally completed
when the capstone was set on December 6, 1884. It was officially dedicated on Feb. 
21, 1885 and opened to the public on October 9, 1888.

Architect Robert Mills

 
Washington monument design by Robert Mills 

Washington monument under construction, about 1860