I'm a sucker for the fascinating borderland where engineering meets architecture and design. Here's a great video of the Falkirk Wheel - a unique way of linking two canals at different levels. Instead of using locks or elevators, the wheel balances two huge troughs full of water. (Since a boat displaces its own weight in water, the tanks always balance whatever the size of boat using the wheel.) Since the wheel is in balance, it takes very little energy to tip the wheel over, rotating the top tank downwards and the bottom tank upwards.
The graceful swan-neck design of the wheel's 'arms', the curves of the supports, the way in which every element of excess mass has been cut away, remind me of the elegance and transparency of Gothic architecture. The need for functionality hasn't been allowed to get in the way of aesthetics - both work together to create a lovely structure. Even better, one in which the movement of the components when it is at work creates even more aesthetic interest; it's like a Calder mobile, meant to be seen when working. Which is why I've given you a link to the video.