The Great Wall of China. How was It built.

[Taltarzac725]

How the Great Wall of China Was Built — Materials, Methods (http://www.chinahighlights.com/greatwall/fact/how-the-great-wall-was-built.htm)

Looked this up in case it gave some hints at how they could also have built the pyramids.

[ColdNoMore]

As a side note, it is an urban myth...that it can be seen with the naked eye from outer space.

[Jima64]

Lots and lots of slaves.

[Arctic Fox]

As a side note, it is an urban myth...that it can be seen with the naked eye from outer space.

There is only one man-made object that can be seen from the International Space Station

[Taltarzac725]

There is only one man-made object that can be seen from the International Space Station

The Greenhouses of Almeria | Amusing Planet (http://www.amusingplanet.com/2013/08/the-greenhouses-of-almeria.html)

Probably this but it looks like many greenhouses in one spot.

[Arctic Fox]

There is only one man-made object that can be seen from the International Space Station

and that is (drumroll, please): the International Space Station