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.
Right now, the Washington Monument has turned out to be one of the United States' most popular structures and one of this country's most important achievements. I am aware that there are other people who question themselves about the real meaning of the Washington Monument. Different books, stories and cinematic movies were produced to try to clarify the genuine meaning and purpose of this impressive structure.