A colossal obelisk erected in honor of George Washington as a national memorial in Washington, DC. The square base of the obelisk measures 55 feet (17 m) on a side, and the tapering hollow shaft, containing a stairway and elevator to the top, is 555 feet (169 m) high. The cornerstone to the monument was laid on July 4, 1848; the monument was finished in 1884 and opened to the public in 1886.