In this article, Cecil states that he doesn’t know who originally stated that the Great Wall of China was the only man-made object observable from space. The answer is Mr. Ripley of “Ripley’s Believe It Or Not” fame. Recently, the History Channel had a biographical piece on Mr. Ripley, and it showed the original column in which Ripley stated this.
when was mr. ripley in space?
… practically always, dave.
If the Great Wall of China was observed in space, then China has one big mother of a rocket! 