Building a wall by precisely stacking randomly shaped boulders could almost be the definition of hard work – both physically and mentally. It's the sort of thing we might want robots to do one day, so it should come as no surprise that one has in fact just done it.
Robotic excavator builds a giant stone wall with no human assistance::undefined
Condensation. Stone wall is cold in the morning, humid morning air passes through it, water condenses on the large, cold surface, and drips down.