Located in Falkirk, Scotland (the same place, I believe, William Wallace went to pick a fight about 750 years ago), the Falkirk Boat Wheel is the first, and only, device of its kind. It's function is to lift and lower boats between the Forth and Clyde Canal and the Union Canal.
I can't do it any justice in writing. Watch the video and you will understand. Is this thing worth the time, money, and effort it clearly took to build? I have no idea, but it is cool to watch: