We can see the Great Wall of China from space.

And we can also see beaver dams from space.

(Note the Great Wall was built for a mundane reason - the Han people couldn't defeat the Mongols on horseback, but they could keep building walls until the horses could no longer enter. Byzantium/Constantinople also adopted that strategy, which worked for over 1,000 years until the Ottomans built the world's largest cannon and blasted holes in it.)