What man-made structure can be seen from space?

You're looking for the answer of 'The Great Wall of China,' but that is not correct! Any number of man-made structures can be seen from space, provided we construe 'structure' to mean 'anything built.' Many of these are things that look like long, straight lines when seen from afar, such as highways, railroads, canals, and of course walls. If the orbit is low enough you can see even more. There is a photo of Cape Canaveral taken during the Gemini V flight in which the big Launch Complex 39, used for the Apollo missions, is clearly visible. Another photo of the Nile delta, taken from a height of 100 miles, shows an extensive road network. Gemini V astronauts Gordon Cooper and Charles Conrad were able to spot, among other things, a special checkerboard pattern that had been laid out in Texas, a rocket-sled test in New Mexico, and the aircraft carrier that would later pick them up in the Atlantic, along with a destroyer trailing in its wake.

If question is asked "...only man made structure able to be seen from the moon" - still NOT the Great Wall. According to NASA, the earth as seen from the moon takes up less than one degree of arc in the sky. Basically it looks like a big blue marble. No man-made detail can be seen at all; sometimes even the continents are barely distinguishable. The NASA folks, I gather, are getting a little tired of hearing about the Great Wall of China. Nobody knows exactly where the story got started, although some think it was speculation by some bigshot during an after-dinner speech in the early days of the space program. The Teeming Millions are humbly requested to give it a rest.Tom Burnam, author of More Misinformation (1980), quotes a letter from astronaut Alan Bean on the subject: "The only thing you can see from the moon is a beautiful sphere, mostly white (clouds), some blue (ocean), patches of yellow (deserts), and every once in a while some green vegetation. No man-made object is visible on this scale. In fact, when first leaving earth's orbit and only a few thousand miles away, no man-made object is visible at that point either."

https://www.nasa.gov/vision/space/workinginspace/great_wall.html

I just got off the telephone with Bill Pogue, astronaut, 3rd crew, Skylab IV, 1973-74. Bill informs me that nothing was 'visible' to the naked eye, except various light patterns and lightening, particularly around the equatorial regions.

At 270 miles distance, with binoculars you can see the following: The China Wall; Grand Canal near Beijing; The Grand Canyon contrast with colors from the mountain snow to reddish-yellow basin; San Francisco, CA Bay area; Kiev industrial areas are easy to see; Aswan Dam in Egypt against the desert terrain; The Nile River for the same reason. The only natural occurrence observed was the Aurora patterns and colors with movement being clearly visible. They tried to see the landing areas at Nazca Planes in Peru, but could not. Photos were taken but were nonconclusive.

Check out his book: 'How Do You Go To The Bathroom In Space' by William R. Pogue, 1999.

I can tell you one thing, contrary to popular belief it is NOT The Great Wall of China....still looking:

http://www.snopes.com/science/greatwall.asp

The moon is roughly 237,000 miles away from us. I don't think anyone with the normal vision can see a a single man-made object from the moon, without the use of high-tech binoculars. Believe in what Apollo 12 astronaut Alan Bean said, "The only thing you can see from the moon is a beautiful sphere, mostly white (clouds), some blue (ocean), patches of yellow (deserts), and every once in a while some green vegetation.

No man-made object is visible on this scale. In fact, when first leaving earth's orbit and only a few thousand miles away, no man-made object is visible at that point either."

The only man made monument visible from moon is...none!

https://www.nasa.gov/vision/space/workinginspace/great_wall.html

There was (and is) more than one manmade structure visible from the moon. The remains of the moon landers are manmade and are still there (unless the Lunarian scrap creatures have removed them...). The question does not state where the manmade structure is to be found, so it does not have to be on the Earth. https://en.wikipedia.org/wiki/Moon_landing

Nor does the question ask about using only the naked human eye. With a telescope many man made structures would be visable from the moon.

http://www.nasa.gov/centers/goddard/news/topstory/2008/lunar_telescopes.html