Ask Marilyn ® by Marilyn vos Savant is a column in Parade Magazine, published by PARADE, 711 Third Avenue, New York, NY 10017, USA. According to Parade, Marilyn vos Savant is listed in the "Guinness Book of World Records Hall of Fame" for "Highest IQ."
In her Parade Magazine column of August 3, 1997, Marilyn reported that the Great Wall of China can not be seen from space.
the astronauts began a series of experiments to test their vision of objects on the ground. Most of the experts tended to disbelieve the reports of earlier astronauts. So for GT-V, special 'eye charts' were laid out in New Mexico and Australia. Cooper and Conrad had no trouble at all in recognizing the signs, even those which they were not supposed to recognize! So excellent did their vision prove that Conrad reported to ground control the presence of a carrier and destroyer at the harbor entrance of Jacksonville. It turned out that the 'carrier' was actually a tugboat and the 'destroyer' a lighter. Such vision at 100 miles (160 km) above the earth seemed rather unbelievable.
Page 39 shows a photo of part of Florida, and you can see highways.
Well, disregarding superman vision, there two reasons why the "wall" would be more visible than lets say, a pyramid. First the wall is a long line, which is a pattern the brain recoognizes. Making up lack of information, joining the dots type of thing. You don't see the wall, you see the line it traces. The second is that the wall makes it's line mostly through dense forest, a high contrast situation. According to Green Peace, you can also distinguish the effects of clear cutting in British Colombia (for the same two reasons).