At first sight, this seems like a propeller about to get attached to an aeroplane engine. I thought the same until I looked closer. Then it blew my mind. Zoom in and discover why.
Yes, it's not a propeller, unless those little bugs in fluorescent vests are gremlins. They are workers about to mount a gigantic propeller on a power windmill turbine. The windmill is one of the two currently being installed in the city of Hamburg, Germany, and it's capable of generating 6 megawatts of energy. Not enough to travel in time, but amazingly cool anyway.