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.
The statue, 151 feet (46 meters) in height, was officially inaugurated in 1886 on Liberty Island, a small island situated at the entrance to New York harbour one kilometer from the landing point of the immigrants, for whom it symbolized the ideals of Washington and Lincoln.