Measuring an astounding total of 21,196 kilometres, the Great Wall of China is indeed the longest man-made structure in the world.

However, even though it boasts such an impressive length, it is only approximately six metres at its widest – at the wall base itself.

This, coupled with the fact that the Great Wall is made of materials that indeed look very similar to the neighbouring terrain, means that the Great Wall is actually not visible from space, even from low Earth orbit at an altitude of some 160km above the Earth’s surface.

There are, indeed, some human structures that are however visible from space, including the Three Gorges Dam in China, the Bingham Canyon Mine located south-east of Salt Lake City and the Palm Jumeirah in Dubai.