Because Ubaid, Sumer, Akkad, Assyria and Babylon civilizations all emerged around the Tigris-Euphrates, the theory that Mesopotamia is the cradle of civilization is widely accepted.
If you Google for washington monument height, the first listing you see is for a page about the monument at greatbuildings.com. Note that the page mentions that the monument has a base of 55 feet and a height of 555 feet, in keeping with what they call the standard Egyptian proportion of 10:1 height to base.
First in War, First in Peace, First in the Hearts of his Countrymen. Built to honor George Washington, the United States' first president, the 555-foot marble obelisk towers over Washington, D.C. The Washington Monument is currently closed to visitors to allow for modernization of the elevator. Link to the Photo Gallery Section.